Python - RS485 Bricklet

This is the description of the Python API bindings for the RS485 Bricklet. General information and technical specifications for the RS485 Bricklet are summarized in its hardware description.

An installation guide for the Python API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Loopback

Download (example_loopback.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

# For this example connect the RX+/- pins to TX+/- pins on the same Bricklet
# and configure the DIP switch on the Bricklet to full-duplex mode

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your RS485 Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_rs485 import BrickletRS485

# Callback function for read callback
def cb_read(message):
    print('Message: "' + ''.join(message) + '"')

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    rs485 = BrickletRS485(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Enable full-duplex mode
    rs485.set_rs485_configuration(115200, rs485.PARITY_NONE, rs485.STOPBITS_1,
                                  rs485.WORDLENGTH_8, rs485.DUPLEX_FULL)

    # Register read callback to function cb_read
    rs485.register_callback(rs485.CALLBACK_READ, cb_read)

    # Enable read callback
    rs485.enable_read_callback()

    # Write "test" string
    rs485.write(list('test'))

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Modbus Master

Download (example_modbus_master.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your RS485 Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_rs485 import BrickletRS485

expected_request_id = None

# Callback function for Modbus master write single register response callback
def cb_modbus_master_write_single_register_response(request_id, exception_code):
    print("Request ID: " + str(request_id))
    print("Exception Code: " + str(exception_code))

    if request_id != expected_request_id:
        print("Error: Unexpected request ID")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    rs485 = BrickletRS485(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Set operating mode to Modbus RTU master
    rs485.set_mode(rs485.MODE_MODBUS_MASTER_RTU)

    # Modbus specific configuration:
    # - slave address = 1 (unused in master mode)
    # - master request timeout = 1000ms
    rs485.set_modbus_configuration(1, 1000)

    # Register Modbus master write single register response callback to function
    # cb_modbus_master_write_single_register_response
    rs485.register_callback(rs485.CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE,
                            cb_modbus_master_write_single_register_response)

    # Write 65535 to register 42 of slave 17
    expected_request_id = rs485.modbus_master_write_single_register(17, 42, 65535)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Modbus Slave

Download (example_modbus_slave.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your RS485 Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_rs485 import BrickletRS485

# Callback function for Modbus slave write single register request callback
def cb_modbus_slave_write_single_register_request(request_id, register_address,
                                                  register_value):
    print("Request ID: " + str(request_id))
    print("Register Address: " + str(register_address))
    print("Register Value: " + str(register_value))

    if register_address != 42:
        print("Error: Invalid register address")
        rs485.modbus_slave_report_exception(request_id, BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS)
    else:
        rs485.modbus_slave_answer_write_single_register_request(request_id)

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    rs485 = BrickletRS485(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Set operating mode to Modbus RTU slave
    rs485.set_mode(rs485.MODE_MODBUS_SLAVE_RTU)

    # Modbus specific configuration:
    # - slave address = 17
    # - master request timeout = 0ms (unused in slave mode)
    rs485.set_modbus_configuration(17, 0)

    # Register Modbus slave write single register request callback to function
    # cb_modbus_slave_write_single_register_request
    rs485.register_callback(rs485.CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST,
                            cb_modbus_slave_write_single_register_request)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Ambient Light Over Modbus

Download (example_ambient_light_over_modbus.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID_RS485 = "XYZ" # Change XYZ to the UID of your RS485 Bricklet
UID_AMBIENT_LIGHT_V3 = "ABC" # Change ABC to the UID of your Ambient Light Bricklet 3.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_rs485 import BrickletRS485
from tinkerforge.bricklet_ambient_light_v3 import BrickletAmbientLightV3

# Callback function for Modbus slave read input registers request callback to expose the
# illuminance value of an Ambient Light Bricklet 3.0 at input register address 42
def cb_modbus_slave_read_input_registers_request(al, request_id, starting_address, count):
    print("Request ID: " + str(request_id))
    print("Starting Address: " + str(starting_address))
    print("Count: " + str(count))

    if starting_address != 42:
        print("Error: Invalid starting address")
        rs485.modbus_slave_report_exception(request_id, BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS)
    elif count != 1:
        print("Error: Invalid count")
        rs485.modbus_slave_report_exception(request_id, BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS)
    else:
        # Get current Illuminance
        illuminance = al.get_illuminance()
        print("Illuminance: " + str(illuminance/100.0) + " lx")

        rs485.modbus_slave_answer_read_input_registers_request(request_id, [illuminance//100])

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    rs485 = BrickletRS485(UID_RS485, ipcon) # Create device object
    al = BrickletAmbientLightV3(UID_AMBIENT_LIGHT_V3, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Set operating mode to Modbus RTU slave
    rs485.set_mode(rs485.MODE_MODBUS_SLAVE_RTU)

    # Modbus specific configuration:
    # - slave address = 17
    # - master request timeout = 0ms (unused in slave mode)
    rs485.set_modbus_configuration(17, 0)

    # Register Modbus slave write single register request callback to function
    # cb_modbus_slave_read_input_registers_request
    rs485.register_callback(rs485.CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST,
                            lambda *args: cb_modbus_slave_read_input_registers_request(al, *args))

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

API

Generally, every function of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

  • Error.TIMEOUT = -1
  • Error.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
  • Error.ALREADY_CONNECTED = -7
  • Error.NOT_CONNECTED = -8
  • Error.INVALID_PARAMETER = -9
  • Error.NOT_SUPPORTED = -10
  • Error.UNKNOWN_ERROR_CODE = -11
  • Error.STREAM_OUT_OF_SYNC = -12
  • Error.INVALID_UID = -13
  • Error.NON_ASCII_CHAR_IN_SECRET = -14

All functions listed below are thread-safe.

Basic Functions

BrickletRS485(uid, ipcon)
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • rs485 – Type: BrickletRS485

Creates an object with the unique device ID uid:

rs485 = BrickletRS485("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected (see examples above).

BrickletRS485.write(message)
Parameters:
  • message – Type: [chr, ...], Length: variable
Returns:
  • message_written – Type: int, Range: [0 to 216 - 1]

Writes characters to the RS485 interface. The characters can be binary data, ASCII or similar is not necessary.

The return value is the number of characters that were written.

See set_rs485_configuration() for configuration possibilities regarding baudrate, parity and so on.

BrickletRS485.read(length)
Parameters:
  • length – Type: int, Range: [0 to 216 - 1]
Returns:
  • message – Type: [chr, ...], Length: variable

Returns up to length characters from receive buffer.

Instead of polling with this function, you can also use callbacks. But note that this function will return available data only when the read callback is disabled. See enable_read_callback() and CALLBACK_READ callback.

BrickletRS485.set_rs485_configuration(baudrate, parity, stopbits, wordlength, duplex)
Parameters:
  • baudrate – Type: int, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: int, Range: See constants, Default: 0
  • stopbits – Type: int, Range: See constants, Default: 1
  • wordlength – Type: int, Range: See constants, Default: 8
  • duplex – Type: int, Range: See constants, Default: 0
Returns:
  • None

Sets the configuration for the RS485 communication.

The following constants are available for this function:

For parity:

  • BrickletRS485.PARITY_NONE = 0
  • BrickletRS485.PARITY_ODD = 1
  • BrickletRS485.PARITY_EVEN = 2

For stopbits:

  • BrickletRS485.STOPBITS_1 = 1
  • BrickletRS485.STOPBITS_2 = 2

For wordlength:

  • BrickletRS485.WORDLENGTH_5 = 5
  • BrickletRS485.WORDLENGTH_6 = 6
  • BrickletRS485.WORDLENGTH_7 = 7
  • BrickletRS485.WORDLENGTH_8 = 8

For duplex:

  • BrickletRS485.DUPLEX_HALF = 0
  • BrickletRS485.DUPLEX_FULL = 1
BrickletRS485.get_rs485_configuration()
Return Object:
  • baudrate – Type: int, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: int, Range: See constants, Default: 0
  • stopbits – Type: int, Range: See constants, Default: 1
  • wordlength – Type: int, Range: See constants, Default: 8
  • duplex – Type: int, Range: See constants, Default: 0

Returns the configuration as set by set_rs485_configuration().

The following constants are available for this function:

For parity:

  • BrickletRS485.PARITY_NONE = 0
  • BrickletRS485.PARITY_ODD = 1
  • BrickletRS485.PARITY_EVEN = 2

For stopbits:

  • BrickletRS485.STOPBITS_1 = 1
  • BrickletRS485.STOPBITS_2 = 2

For wordlength:

  • BrickletRS485.WORDLENGTH_5 = 5
  • BrickletRS485.WORDLENGTH_6 = 6
  • BrickletRS485.WORDLENGTH_7 = 7
  • BrickletRS485.WORDLENGTH_8 = 8

For duplex:

  • BrickletRS485.DUPLEX_HALF = 0
  • BrickletRS485.DUPLEX_FULL = 1
BrickletRS485.set_modbus_configuration(slave_address, master_request_timeout)
Parameters:
  • slave_address – Type: int, Range: [1 to 247], Default: 1
  • master_request_timeout – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 1000
Returns:
  • None

Sets the configuration for the RS485 Modbus communication. Available options:

  • Slave Address: Address to be used as the Modbus slave address in Modbus slave mode. Valid Modbus slave address range is 1 to 247.
  • Master Request Timeout: Specifies how long the master should wait for a response from a slave when in Modbus master mode.
BrickletRS485.get_modbus_configuration()
Return Object:
  • slave_address – Type: int, Range: [1 to 247], Default: 1
  • master_request_timeout – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 1000

Returns the configuration as set by set_modbus_configuration().

BrickletRS485.set_mode(mode)
Parameters:
  • mode – Type: int, Range: See constants, Default: 0
Returns:
  • None

Sets the mode of the Bricklet in which it operates. Available options are

  • RS485,
  • Modbus Master RTU and
  • Modbus Slave RTU.

The following constants are available for this function:

For mode:

  • BrickletRS485.MODE_RS485 = 0
  • BrickletRS485.MODE_MODBUS_MASTER_RTU = 1
  • BrickletRS485.MODE_MODBUS_SLAVE_RTU = 2
BrickletRS485.get_mode()
Returns:
  • mode – Type: int, Range: See constants, Default: 0

Returns the configuration as set by set_mode().

The following constants are available for this function:

For mode:

  • BrickletRS485.MODE_RS485 = 0
  • BrickletRS485.MODE_MODBUS_MASTER_RTU = 1
  • BrickletRS485.MODE_MODBUS_SLAVE_RTU = 2

Advanced Functions

BrickletRS485.set_communication_led_config(config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3
Returns:
  • None

Sets the communication LED configuration. By default the LED shows RS485 communication traffic by flickering.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

  • BrickletRS485.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletRS485.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
BrickletRS485.get_communication_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_communication_led_config()

The following constants are available for this function:

For config:

  • BrickletRS485.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletRS485.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
BrickletRS485.set_error_led_config(config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3
Returns:
  • None

Sets the error LED configuration.

By default the error LED turns on if there is any error (see CALLBACK_ERROR_COUNT callback). If you call this function with the SHOW ERROR option again, the LED will turn off until the next error occurs.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

  • BrickletRS485.ERROR_LED_CONFIG_OFF = 0
  • BrickletRS485.ERROR_LED_CONFIG_ON = 1
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_ERROR = 3
BrickletRS485.get_error_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_error_led_config().

The following constants are available for this function:

For config:

  • BrickletRS485.ERROR_LED_CONFIG_OFF = 0
  • BrickletRS485.ERROR_LED_CONFIG_ON = 1
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_ERROR = 3
BrickletRS485.set_buffer_config(send_buffer_size, receive_buffer_size)
Parameters:
  • send_buffer_size – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receive_buffer_size – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120
Returns:
  • None

Sets the send and receive buffer size in byte. In sum there is 10240 byte (10KiB) buffer available and the minimum buffer size is 1024 byte (1KiB) for both.

The current buffer content is lost if this function is called.

The send buffer holds data that was given by write() and could not be written yet. The receive buffer holds data that is received through RS485 but could not yet be send to the user, either by read() or through CALLBACK_READ callback.

BrickletRS485.get_buffer_config()
Return Object:
  • send_buffer_size – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receive_buffer_size – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120

Returns the buffer configuration as set by set_buffer_config().

BrickletRS485.get_buffer_status()
Return Object:
  • send_buffer_used – Type: int, Unit: 1 B, Range: [1024 to 9216]
  • receive_buffer_used – Type: int, Unit: 1 B, Range: [1024 to 9216]

Returns the currently used bytes for the send and received buffer.

See set_buffer_config() for buffer size configuration.

BrickletRS485.get_error_count()
Return Object:
  • overrun_error_count – Type: int, Range: [0 to 232 - 1]
  • parity_error_count – Type: int, Range: [0 to 232 - 1]

Returns the current number of overrun and parity errors.

BrickletRS485.get_modbus_common_error_count()
Return Object:
  • timeout_error_count – Type: int, Range: [0 to 232 - 1]
  • checksum_error_count – Type: int, Range: [0 to 232 - 1]
  • frame_too_big_error_count – Type: int, Range: [0 to 232 - 1]
  • illegal_function_error_count – Type: int, Range: [0 to 232 - 1]
  • illegal_data_address_error_count – Type: int, Range: [0 to 232 - 1]
  • illegal_data_value_error_count – Type: int, Range: [0 to 232 - 1]
  • slave_device_failure_error_count – Type: int, Range: [0 to 232 - 1]

Returns the current number of errors occurred in Modbus mode.

  • Timeout Error Count: Number of timeouts occurred.
  • Checksum Error Count: Number of failures due to Modbus frame CRC16 checksum mismatch.
  • Frame Too Big Error Count: Number of times frames were rejected because they exceeded maximum Modbus frame size which is 256 bytes.
  • Illegal Function Error Count: Number of errors when an unimplemented or illegal function is requested. This corresponds to Modbus exception code 1.
  • Illegal Data Address Error Count: Number of errors due to invalid data address. This corresponds to Modbus exception code 2.
  • Illegal Data Value Error Count: Number of errors due to invalid data value. This corresponds to Modbus exception code 3.
  • Slave Device Failure Error Count: Number of errors occurred on the slave device which were unrecoverable. This corresponds to Modbus exception code 4.
BrickletRS485.modbus_slave_report_exception(request_id, exception_code)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants
Returns:
  • None

In Modbus slave mode this function can be used to report a Modbus exception for a Modbus master request.

  • Request ID: Request ID of the request received by the slave.
  • Exception Code: Modbus exception code to report to the Modbus master.

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.modbus_slave_answer_read_coils_request(request_id, coils)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • coils – Type: [bool, ...], Length: variable
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to read coils.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Coils: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST callback with the Request ID as provided by the argument of the callback.

BrickletRS485.modbus_master_read_coils(slave_address, starting_address, count)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 2000]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to read coils from a slave. This function creates a Modbus function code 1 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first coil to read. For backwards compatibility reasons this parameter is called Starting Address. It is not an address, but instead a coil number in the range of 1 to 65536.
  • Count: Number of coils to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_READ_COILS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_read_holding_registers_request(request_id, holding_registers)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • holding_registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to read holding registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Holding Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

BrickletRS485.modbus_master_read_holding_registers(slave_address, starting_address, count)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 125]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to read holding registers from a slave. This function creates a Modbus function code 3 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first holding register to read. For backwards compatibility reasons this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.
  • Count: Number of holding registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_READ_HOLDING_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_write_single_coil_request(request_id)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to write a single coil.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST callback with the Request ID as provided by the arguments of the callback.

BrickletRS485.modbus_master_write_single_coil(slave_address, coil_address, coil_value)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • coil_address – Type: int, Range: [1 to 65536]
  • coil_value – Type: bool
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to write a single coil of a slave. This function creates a Modbus function code 5 request.

  • Slave Address: Address of the target Modbus slave.
  • Coil Address: Number of the coil to be written. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a coil number in the range of 1 to 65536.
  • Coil Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_WRITE_SINGLE_COIL_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_write_single_register_request(request_id)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to write a single register.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST callback with the Request ID, Register Address and Register Value as provided by the arguments of the callback.

BrickletRS485.modbus_master_write_single_register(slave_address, register_address, register_value)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • register_address – Type: int, Range: [1 to 65536]
  • register_value – Type: int, Range: [0 to 216 - 1]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to write a single holding register of a slave. This function creates a Modbus function code 6 request.

  • Slave Address: Address of the target Modbus slave.
  • Register Address: Number of the holding register to be written. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.
  • Register Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_write_multiple_coils_request(request_id)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to write multiple coils.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST callback with the Request ID of the callback.

BrickletRS485.modbus_master_write_multiple_coils(slave_address, starting_address, coils)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • coils – Type: [bool, ...], Length: variable
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to write multiple coils of a slave. This function creates a Modbus function code 15 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first coil to write. For backwards compatibility reasons, this parameter is called Starting Address.It is not an address, but instead a coil number in the range of 1 to 65536.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_COILS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_write_multiple_registers_request(request_id)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to write multiple registers.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST callback with the Request ID of the callback.

BrickletRS485.modbus_master_write_multiple_registers(slave_address, starting_address, registers)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to write multiple registers of a slave. This function creates a Modbus function code 16 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first holding register to write. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_read_discrete_inputs_request(request_id, discrete_inputs)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • discrete_inputs – Type: [bool, ...], Length: variable
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to read discrete inputs.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Discrete Inputs: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST callback with the Request ID as provided by the argument of the callback.

BrickletRS485.modbus_master_read_discrete_inputs(slave_address, starting_address, count)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 2000]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to read discrete inputs from a slave. This function creates a Modbus function code 2 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first discrete input to read. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a discrete input number in the range of 1 to 65536. The prefix digit 1 (for discrete input) is implicit and must be omitted.
  • Count: Number of discrete inputs to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_READ_DISCRETE_INPUTS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.modbus_slave_answer_read_input_registers_request(request_id, input_registers)
Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • input_registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]
Returns:
  • None

In Modbus slave mode this function can be used to answer a master request to read input registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Input Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

BrickletRS485.modbus_master_read_input_registers(slave_address, starting_address, count)
Parameters:
  • slave_address – Type: int, Range: [0 to 247]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 125]
Returns:
  • request_id – Type: int, Range: [0 to 255]

In Modbus master mode this function can be used to read input registers from a slave. This function creates a Modbus function code 4 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first input register to read. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead an input register number in the range of 1 to 65536. The prefix digit 3 (for input register) is implicit and must be omitted.
  • Count: Number of input registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the CALLBACK_MODBUS_MASTER_READ_INPUT_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

BrickletRS485.get_spitfp_error_count()
Return Object:
  • error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_frame – Type: int, Range: [0 to 232 - 1]
  • error_count_overflow – Type: int, Range: [0 to 232 - 1]

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

BrickletRS485.set_bootloader_mode(mode)
Parameters:
  • mode – Type: int, Range: See constants
Returns:
  • status – Type: int, Range: See constants

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

For mode:

  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

  • BrickletRS485.BOOTLOADER_STATUS_OK = 0
  • BrickletRS485.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletRS485.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletRS485.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletRS485.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletRS485.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletRS485.get_bootloader_mode()
Returns:
  • mode – Type: int, Range: See constants

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

For mode:

  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletRS485.set_write_firmware_pointer(pointer)
Parameters:
  • pointer – Type: int, Unit: 1 B, Range: [0 to 232 - 1]
Returns:
  • None

Sets the firmware pointer for write_firmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletRS485.write_firmware(data)
Parameters:
  • data – Type: [int, ...], Length: 64, Range: [0 to 255]
Returns:
  • status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by set_write_firmware_pointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletRS485.set_status_led_config(config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3
Returns:
  • None

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

For config:

  • BrickletRS485.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS485.STATUS_LED_CONFIG_ON = 1
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletRS485.get_status_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

For config:

  • BrickletRS485.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS485.STATUS_LED_CONFIG_ON = 1
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletRS485.get_chip_temperature()
Returns:
  • temperature – Type: int, Unit: 1 °C, Range: [-215 to 215 - 1]

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

BrickletRS485.reset()
Returns:
  • None

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

BrickletRS485.write_uid(uid)
Parameters:
  • uid – Type: int, Range: [0 to 232 - 1]
Returns:
  • None

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

BrickletRS485.read_uid()
Returns:
  • uid – Type: int, Range: [0 to 232 - 1]

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

BrickletRS485.get_identity()
Return Object:
  • uid – Type: str, Length: up to 8
  • connected_uid – Type: str, Length: up to 8
  • position – Type: chr, Range: ["a" to "i", "z"]
  • hardware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • device_identifier – Type: int, Range: [0 to 216 - 1]

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

BrickletRS485.register_callback(callback_id, function)
Parameters:
  • callback_id – Type: int
  • function – Type: callable
Returns:
  • None

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletRS485.enable_read_callback()
Returns:
  • None

Enables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS485.disable_read_callback()
Returns:
  • None

Disables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS485.is_read_callback_enabled()
Returns:
  • enabled – Type: bool, Default: False

Returns true if the CALLBACK_READ callback is enabled, false otherwise.

BrickletRS485.enable_error_count_callback()
Returns:
  • None

Enables the CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

BrickletRS485.disable_error_count_callback()
Returns:
  • None

Disables the CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

BrickletRS485.is_error_count_callback_enabled()
Returns:
  • enabled – Type: bool, Default: True

Returns true if the CALLBACK_ERROR_COUNT callback is enabled, false otherwise.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

rs485.register_callback(BrickletRS485.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

BrickletRS485.CALLBACK_READ
Callback Parameters:
  • message – Type: [chr, ...], Length: variable

This callback is called if new data is available.

To enable this callback, use enable_read_callback().

Note

If reconstructing the value fails, the callback is triggered with None for message.

BrickletRS485.CALLBACK_ERROR_COUNT
Callback Parameters:
  • overrun_error_count – Type: int, Range: [0 to 232 - 1]
  • parity_error_count – Type: int, Range: [0 to 232 - 1]

This callback is called if a new error occurs. It returns the current overrun and parity error count.

BrickletRS485.CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 2000]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read coils. The parameters are request ID of the request, the number of the first coil to be read and the number of coils to be read as received by the request. The number of the first coil is called starting address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use modbus_slave_answer_read_coils_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_READ_COILS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants
  • coils – Type: [bool, ...], Length: variable

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with None for coils.

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 125]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read holding registers. The parameters are request ID of the request, the number of the first holding register to be read and the number of holding registers to be read as received by the request. The number of the first holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use modbus_slave_answer_read_holding_registers_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_READ_HOLDING_REGISTERS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants
  • holding_registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]

This callback is called only in Modbus master mode when the master receives a valid response of a request to read holding registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with None for holding_registers.

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • coil_address – Type: int, Range: [1 to 65536]
  • coil_value – Type: bool

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single coil. The parameters are request ID of the request, the number of the coil and the value of coil to be written as received by the request. The number of the coil is called coil address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use modbus_slave_answer_write_single_coil_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_WRITE_SINGLE_COIL_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single coil.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • register_address – Type: int, Range: [1 to 65536]
  • register_value – Type: int, Range: [0 to 216 - 1]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single holding register. The parameters are request ID of the request, the number of the holding register and the register value to be written as received by the request. The number of the holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use modbus_slave_answer_write_single_register_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single register.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • coils – Type: [bool, ...], Length: variable

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple coils. The parameters are request ID of the request, the number of the first coil and the data to be written as received by the request. The number of the first coil is called starting address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use modbus_slave_answer_write_multiple_coils_request().

Note

If reconstructing the value fails, the callback is triggered with None for coils.

BrickletRS485.CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_COILS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple holding registers. The parameters are request ID of the request, the number of the first holding register and the data to be written as received by the request. The number of the first holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use modbus_slave_answer_write_multiple_registers_request().

Note

If reconstructing the value fails, the callback is triggered with None for registers.

BrickletRS485.CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_REGISTERS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants

This callback is called only in Modbus master mode when the master receives a valid response of a request to write multiple registers.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 2000]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read discrete inputs. The parameters are request ID of the request, the number of the first discrete input and the number of discrete inputs to be read as received by the request. The number of the first discrete input is called starting address for backwards compatibility reasons. It is not an address, but instead a discrete input number in the range of 1 to 65536. The prefix digit 1 (for discrete input) is omitted.

To send a response of this request use modbus_slave_answer_read_discrete_inputs_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_READ_DISCRETE_INPUTS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants
  • discrete_inputs – Type: [bool, ...], Length: variable

This callback is called only in Modbus master mode when the master receives a valid response of a request to read discrete inputs.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with None for discrete_inputs.

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
BrickletRS485.CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • starting_address – Type: int, Range: [1 to 65536]
  • count – Type: int, Range: [1 to 125]

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read input registers. The parameters are request ID of the request, the number of the first input register and the number of input registers to be read as received by the request. The number of the first input register is called starting address for backwards compatibility reasons. It is not an address, but instead a input register number in the range of 1 to 65536. The prefix digit 3 (for input register) is omitted.

To send a response of this request use modbus_slave_answer_read_input_registers_request().

BrickletRS485.CALLBACK_MODBUS_MASTER_READ_INPUT_REGISTERS_RESPONSE
Callback Parameters:
  • request_id – Type: int, Range: [0 to 255]
  • exception_code – Type: int, Range: See constants
  • input_registers – Type: [int, ...], Length: variable, Range: [0 to 216 - 1]

This callback is called only in Modbus master mode when the master receives a valid response of a request to read input registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with None for input_registers.

The following constants are available for this function:

For exception_code:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickletRS485.get_api_version()
Return Object:
  • api_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]

Returns the version of the API definition implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickletRS485.get_response_expected(function_id)
Parameters:
  • function_id – Type: int, Range: See constants
Returns:
  • response_expected – Type: bool

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by set_response_expected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletRS485.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS485.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS485.FUNCTION_SET_RS485_CONFIGURATION = 6
  • BrickletRS485.FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • BrickletRS485.FUNCTION_SET_MODE = 10
  • BrickletRS485.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • BrickletRS485.FUNCTION_SET_ERROR_LED_CONFIG = 14
  • BrickletRS485.FUNCTION_SET_BUFFER_CONFIG = 16
  • BrickletRS485.FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • BrickletRS485.FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • BrickletRS485.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletRS485.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletRS485.FUNCTION_RESET = 243
  • BrickletRS485.FUNCTION_WRITE_UID = 248
BrickletRS485.set_response_expected(function_id, response_expected)
Parameters:
  • function_id – Type: int, Range: See constants
  • response_expected – Type: bool
Returns:
  • None

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletRS485.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS485.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS485.FUNCTION_SET_RS485_CONFIGURATION = 6
  • BrickletRS485.FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • BrickletRS485.FUNCTION_SET_MODE = 10
  • BrickletRS485.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • BrickletRS485.FUNCTION_SET_ERROR_LED_CONFIG = 14
  • BrickletRS485.FUNCTION_SET_BUFFER_CONFIG = 16
  • BrickletRS485.FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • BrickletRS485.FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • BrickletRS485.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletRS485.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletRS485.FUNCTION_RESET = 243
  • BrickletRS485.FUNCTION_WRITE_UID = 248
BrickletRS485.set_response_expected_all(response_expected)
Parameters:
  • response_expected – Type: bool
Returns:
  • None

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Constants

BrickletRS485.DEVICE_IDENTIFIER

This constant is used to identify a RS485 Bricklet.

The get_identity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletRS485.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS485 Bricklet.