Modbus - RS232 Bricklet 2.0

This is the description of the Modbus protocol for the RS232 Bricklet 2.0. General information and technical specifications for the RS232 Bricklet 2.0 are summarized in its hardware description.

API

A general description of the Modbus protocol structure can be found here.

Basic Functions

BrickletRS232V2.write_low_level
Function ID:
  • 1
Request:
  • message_length – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_offset – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_data – Type: char[60]
Response:
  • message_chunk_written – Type: uint8, Range: [0 to 255]

Writes characters to the RS232 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_configuration for configuration possibilities regarding baud rate, parity and so on.

BrickletRS232V2.read_low_level
Function ID:
  • 2
Request:
  • length – Type: uint16, Range: [0 to 216 - 1]
Response:
  • message_length – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_offset – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_data – Type: char[60]

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_LOW_LEVEL callback.

BrickletRS232V2.set_configuration
Function ID:
  • 6
Request:
  • baudrate – Type: uint32, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: uint8, Range: See meanings, Default: 0
  • stopbits – Type: uint8, Range: See meanings, Default: 1
  • wordlength – Type: uint8, Range: See meanings, Default: 8
  • flowcontrol – Type: uint8, Range: See meanings, Default: 0
Response:
  • no response

Sets the configuration for the RS232 communication.

The following meanings are defined for the elements of this function:

For parity:

  • 0 = None
  • 1 = Odd
  • 2 = Even

For stopbits:

  • 1 = 1
  • 2 = 2

For wordlength:

  • 5 = 5
  • 6 = 6
  • 7 = 7
  • 8 = 8

For flowcontrol:

  • 0 = Off
  • 1 = Software
  • 2 = Hardware
BrickletRS232V2.get_configuration
Function ID:
  • 7
Request:
  • empty payload
Response:
  • baudrate – Type: uint32, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: uint8, Range: See meanings, Default: 0
  • stopbits – Type: uint8, Range: See meanings, Default: 1
  • wordlength – Type: uint8, Range: See meanings, Default: 8
  • flowcontrol – Type: uint8, Range: See meanings, Default: 0

Returns the configuration as set by set_configuration.

The following meanings are defined for the elements of this function:

For parity:

  • 0 = None
  • 1 = Odd
  • 2 = Even

For stopbits:

  • 1 = 1
  • 2 = 2

For wordlength:

  • 5 = 5
  • 6 = 6
  • 7 = 7
  • 8 = 8

For flowcontrol:

  • 0 = Off
  • 1 = Software
  • 2 = Hardware

Advanced Functions

BrickletRS232V2.set_buffer_config
Function ID:
  • 8
Request:
  • send_buffer_size – Type: uint16, Unit: 1 B, Range: [210 to 9216], Default: 5120
  • receive_buffer_size – Type: uint16, Unit: 1 B, Range: [210 to 9216], Default: 5120
Response:
  • no response

Sets the send and receive buffer size in byte. In total the buffers have to be 10240 byte (10KiB) in size, the minimum buffer size is 1024 byte (1KiB) for each.

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

The send buffer holds data that is given by write_low_level and can not be written yet. The receive buffer holds data that is received through RS232 but could not yet be send to the user, either by read_low_level or through CALLBACK_READ_LOW_LEVEL callback.

BrickletRS232V2.get_buffer_config
Function ID:
  • 9
Request:
  • empty payload
Response:
  • send_buffer_size – Type: uint16, Unit: 1 B, Range: [210 to 9216], Default: 5120
  • receive_buffer_size – Type: uint16, Unit: 1 B, Range: [210 to 9216], Default: 5120

Returns the buffer configuration as set by set_buffer_config.

BrickletRS232V2.get_buffer_status
Function ID:
  • 10
Request:
  • empty payload
Response:
  • send_buffer_used – Type: uint16, Unit: 1 B, Range: [0 to 9216]
  • receive_buffer_used – Type: uint16, Unit: 1 B, Range: [0 to 9216]

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

See set_buffer_config for buffer size configuration.

BrickletRS232V2.get_error_count
Function ID:
  • 11
Request:
  • empty payload
Response:
  • error_count_overrun – Type: uint32, Range: [0 to 232 - 1]
  • error_count_parity – Type: uint32, Range: [0 to 232 - 1]

Returns the current number of overrun and parity errors.

BrickletRS232V2.get_spitfp_error_count
Function ID:
  • 234
Request:
  • empty payload
Response:
  • error_count_ack_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_frame – Type: uint32, Range: [0 to 232 - 1]
  • error_count_overflow – Type: uint32, 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.

BrickletRS232V2.set_status_led_config
Function ID:
  • 239
Request:
  • config – Type: uint8, Range: See meanings, Default: 3
Response:
  • no response

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 meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletRS232V2.get_status_led_config
Function ID:
  • 240
Request:
  • empty payload
Response:
  • config – Type: uint8, Range: See meanings, Default: 3

Returns the configuration as set by set_status_led_config

The following meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletRS232V2.get_chip_temperature
Function ID:
  • 242
Request:
  • empty payload
Response:
  • temperature – Type: int16, 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.

BrickletRS232V2.reset
Function ID:
  • 243
Request:
  • empty payload
Response:
  • no response

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!

BrickletRS232V2.get_identity
Function ID:
  • 255
Request:
  • empty payload
Response:
  • uid – Type: char[8]
  • connected_uid – Type: char[8]
  • position – Type: char, Range: ['a' to 'h', 'z']
  • hardware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • firmware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • device_identifier – Type: uint16, 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). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here

Callback Configuration Functions

BrickletRS232V2.enable_read_callback
Function ID:
  • 3
Request:
  • empty payload
Response:
  • no response

Enables the CALLBACK_READ_LOW_LEVEL callback. This will disable the CALLBACK_FRAME_READABLE callback.

By default the callback is disabled.

BrickletRS232V2.disable_read_callback
Function ID:
  • 4
Request:
  • empty payload
Response:
  • no response

Disables the CALLBACK_READ_LOW_LEVEL callback.

By default the callback is disabled.

BrickletRS232V2.is_read_callback_enabled
Function ID:
  • 5
Request:
  • empty payload
Response:
  • enabled – Type: bool, Default: false

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

BrickletRS232V2.set_frame_readable_callback_configuration
Function ID:
  • 14
Request:
  • frame_size – Type: uint16, Unit: 1 B, Range: [0 to 9216], Default: 0
Response:
  • no response

Configures the CALLBACK_FRAME_READABLE callback. The frame size is the number of bytes, that have to be readable to trigger the callback. A frame size of 0 disables the callback. A frame size greater than 0 enables the callback and disables the CALLBACK_READ_LOW_LEVEL callback.

By default the callback is disabled.

New in version 2.0.3 (Plugin).

BrickletRS232V2.get_frame_readable_callback_configuration
Function ID:
  • 15
Request:
  • empty payload
Response:
  • frame_size – Type: uint16, Unit: 1 B, Range: [0 to 9216], Default: 0

Returns the callback configuration as set by set_frame_readable_callback_configuration.

New in version 2.0.3 (Plugin).

Callbacks

BrickletRS232V2.CALLBACK_READ_LOW_LEVEL
Function ID:
  • 12
Response:
  • message_length – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_offset – Type: uint16, Range: [0 to 216 - 1]
  • message_chunk_data – Type: char[60]

This callback is called if new data is available.

To enable this callback, use enable_read_callback.

BrickletRS232V2.CALLBACK_ERROR_COUNT
Function ID:
  • 13
Response:
  • error_count_overrun – Type: uint32, Range: [0 to 232 - 1]
  • error_count_parity – Type: uint32, Range: [0 to 232 - 1]

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

BrickletRS232V2.CALLBACK_FRAME_READABLE
Function ID:
  • 16
Response:
  • frame_count – Type: uint16, Range: [0 to 216 - 1]

This callback is called if at least one frame of data is readable. The frame size is configured with set_frame_readable_callback_configuration. The frame count parameter is the number of frames that can be read. This callback is triggered only once until read_low_level is called. This means, that if you have configured a frame size of X bytes, you can read exactly X bytes using the read_low_level function, every time the callback triggers without checking the frame count response value.

New in version 2.0.3 (Plugin).

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

BrickletRS232V2.set_bootloader_mode
Function ID:
  • 235
Request:
  • mode – Type: uint8, Range: See meanings
Response:
  • status – Type: uint8, Range: See meanings

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 meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot

For status:

  • 0 = OK
  • 1 = Invalid Mode
  • 2 = No Change
  • 3 = Entry Function Not Present
  • 4 = Device Identifier Incorrect
  • 5 = CRC Mismatch
BrickletRS232V2.get_bootloader_mode
Function ID:
  • 236
Request:
  • empty payload
Response:
  • mode – Type: uint8, Range: See meanings

Returns the current bootloader mode, see set_bootloader_mode.

The following meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot
BrickletRS232V2.set_write_firmware_pointer
Function ID:
  • 237
Request:
  • pointer – Type: uint32, Unit: 1 B, Range: [0 to 232 - 1]
Response:
  • no response

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.

BrickletRS232V2.write_firmware
Function ID:
  • 238
Request:
  • data – Type: uint8[64], Range: [0 to 255]
Response:
  • status – Type: uint8, 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.

BrickletRS232V2.write_uid
Function ID:
  • 248
Request:
  • uid – Type: uint32, Range: [0 to 232 - 1]
Response:
  • no response

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.

BrickletRS232V2.read_uid
Function ID:
  • 249
Request:
  • empty payload
Response:
  • uid – Type: uint32, Range: [0 to 232 - 1]

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