C/C++ - RS485 Bricklet

This is the description of the C/C++ 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 C/C++ API bindings is part of their general description.

Examples

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

Modbus Master

Download (example_modbus_master.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_rs485.h"

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

// Callback function for Modbus master write single register response callback
void cb_modbus_master_write_single_register_response(uint8_t request_id,
                                                     int8_t exception_code,
                                                     void *user_data) {
    uint8_t expected_request_id = *(uint8_t *)user_data;

    printf("Request ID: %d\n", request_id);
    printf("Exception Code: %d\n", exception_code);

    if (request_id != expected_request_id) {
        printf("Error: Unexpected request ID\n");
    }
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Set operating mode to Modbus RTU master
    rs485_set_mode(&rs485, RS485_MODE_MODBUS_MASTER_RTU);

    // Modbus specific configuration:
    // - slave address = 1 (unused in master mode)
    // - master request timeout = 1000ms
    rs485_set_modbus_configuration(&rs485, 1, 1000);

    // Register Modbus master write single register response callback to function
    // cb_modbus_master_write_single_register_response
    uint8_t expected_request_id = 0;
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE,
                            (void *)cb_modbus_master_write_single_register_response,
                            (void *)&expected_request_id);

    // Write 65535 to register 42 of slave 17
    rs485_modbus_master_write_single_register(&rs485, 17, 42, 65535, &expected_request_id);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Modbus Slave

Download (example_modbus_slave.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_rs485.h"

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

// Callback function for Modbus slave write single register request callback
void cb_modbus_slave_write_single_register_request(uint8_t request_id,
                                                   uint32_t register_address,
                                                   uint16_t register_value,
                                                   void *user_data) {
    RS485 *rs485 = (RS485 *)user_data;

    printf("Request ID: %d\n", request_id);
    printf("Register Address: %d\n", register_address);
    printf("Register Value: %d\n", register_value);

    if (register_address != 42) {
        printf("Error: Invalid register address\n");
        rs485_modbus_slave_report_exception(rs485, request_id, RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS);
    } else {
        rs485_modbus_slave_answer_write_single_register_request(rs485, request_id);
    }
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Set operating mode to Modbus RTU slave
    rs485_set_mode(&rs485, RS485_MODE_MODBUS_SLAVE_RTU);

    // Modbus specific configuration:
    // - slave address = 17
    // - master request timeout = 0ms (unused in slave mode)
    rs485_set_modbus_configuration(&rs485, 17, 0);

    // Register Modbus slave write single register request callback to function
    // cb_modbus_slave_write_single_register_request
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST,
                            (void *)cb_modbus_slave_write_single_register_request,
                            (void *)&rs485);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Loopback

Download (example_loopback.c)

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#include <stdio.h>
#include <stdlib.h>

// 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

#include "ip_connection.h"
#include "bricklet_rs485.h"

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

// Callback function for read callback
void cb_read(char *message, uint16_t message_length, void *user_data) {
    char *buffer;

    (void)user_data; // avoid unused parameter warning

    // Assume that the message consists of ASCII characters and
    // convert it from an array of chars to a NUL-terminated string
    buffer = (char *)malloc(message_length + 1); // +1 for the NUL-terminator
    memcpy(buffer, message, message_length);
    buffer[message_length] = '\0';

    printf("Message: \"%s\"\n", buffer);
    free(buffer);
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Enable full-duplex mode
    rs485_set_rs485_configuration(&rs485, 115200, RS485_PARITY_NONE, RS485_STOPBITS_1,
                                  RS485_WORDLENGTH_8, RS485_DUPLEX_FULL);

    // Register read callback to function cb_read
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_READ,
                            (void *)cb_read,
                            NULL);

    // Enable read callback
    rs485_enable_read_callback(&rs485);

    // Write "test" string
    char buffer[] = {'t', 'e', 's', 't'};
    uint16_t written;
    rs485_write(&rs485, buffer, sizeof(buffer), &written);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

API

Every function of the C/C++ bindings returns an integer which describes an error code. Data returned from the device, when a getter is called, is handled via call by reference. These parameters are labeled with the ret_ prefix.

Possible error codes are:

  • E_OK = 0
  • E_TIMEOUT = -1
  • E_NO_STREAM_SOCKET = -2
  • E_HOSTNAME_INVALID = -3
  • E_NO_CONNECT = -4
  • E_NO_THREAD = -5
  • E_NOT_ADDED = -6 (unused since bindings version 2.0.0)
  • E_ALREADY_CONNECTED = -7
  • E_NOT_CONNECTED = -8
  • E_INVALID_PARAMETER = -9
  • E_NOT_SUPPORTED = -10
  • E_UNKNOWN_ERROR_CODE = -11
  • E_STREAM_OUT_OF_SYNC = -12

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void rs485_create(RS485 *rs485, const char *uid, IPConnection *ipcon)

Creates the device object rs485 with the unique device ID uid and adds it to the IPConnection ipcon:

RS485 rs485;
rs485_create(&rs485, "YOUR_DEVICE_UID", &ipcon);

This device object can be used after the IP connection has been connected (see examples above).

void rs485_destroy(RS485 *rs485)

Removes the device object rs485 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int rs485_write(RS485 *rs485, const char *message, uint16_t message_length, uint16_t *ret_message_written)

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 rs485_set_rs485_configuration() for configuration possibilities regarding baudrate, parity and so on.

int rs485_read(RS485 *rs485, uint16_t length, char *ret_message, uint16_t *ret_message_length)

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 rs485_enable_read_callback() and RS485_CALLBACK_READ callback.

int rs485_set_rs485_configuration(RS485 *rs485, uint32_t baudrate, uint8_t parity, uint8_t stopbits, uint8_t wordlength, uint8_t duplex)

Sets the configuration for the RS485 communication. Available options:

  • Baudrate between 100 and 2000000 baud.
  • Parity of none, odd or even.
  • Stopbits can be 1 or 2.
  • Word length of 5 to 8.
  • Half- or Full-Duplex.

The default is: 115200 baud, parity none, 1 stop bit, word length 8, half duplex.

The following defines are available for this function:

  • RS485_PARITY_NONE = 0
  • RS485_PARITY_ODD = 1
  • RS485_PARITY_EVEN = 2
  • RS485_STOPBITS_1 = 1
  • RS485_STOPBITS_2 = 2
  • RS485_WORDLENGTH_5 = 5
  • RS485_WORDLENGTH_6 = 6
  • RS485_WORDLENGTH_7 = 7
  • RS485_WORDLENGTH_8 = 8
  • RS485_DUPLEX_HALF = 0
  • RS485_DUPLEX_FULL = 1
int rs485_get_rs485_configuration(RS485 *rs485, uint32_t *ret_baudrate, uint8_t *ret_parity, uint8_t *ret_stopbits, uint8_t *ret_wordlength, uint8_t *ret_duplex)

Returns the configuration as set by rs485_set_rs485_configuration().

The following defines are available for this function:

  • RS485_PARITY_NONE = 0
  • RS485_PARITY_ODD = 1
  • RS485_PARITY_EVEN = 2
  • RS485_STOPBITS_1 = 1
  • RS485_STOPBITS_2 = 2
  • RS485_WORDLENGTH_5 = 5
  • RS485_WORDLENGTH_6 = 6
  • RS485_WORDLENGTH_7 = 7
  • RS485_WORDLENGTH_8 = 8
  • RS485_DUPLEX_HALF = 0
  • RS485_DUPLEX_FULL = 1
int rs485_set_modbus_configuration(RS485 *rs485, uint8_t slave_address, uint32_t master_request_timeout)

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 in milliseconds when in Modbus master mode.

The default is: Slave Address = 1 and Master Request Timeout = 1000 milliseconds (1 second).

int rs485_get_modbus_configuration(RS485 *rs485, uint8_t *ret_slave_address, uint32_t *ret_master_request_timeout)

Returns the configuration as set by rs485_set_modbus_configuration().

int rs485_set_mode(RS485 *rs485, uint8_t mode)

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

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

The default is: RS485 mode.

The following defines are available for this function:

  • RS485_MODE_RS485 = 0
  • RS485_MODE_MODBUS_MASTER_RTU = 1
  • RS485_MODE_MODBUS_SLAVE_RTU = 2
int rs485_get_mode(RS485 *rs485, uint8_t *ret_mode)

Returns the configuration as set by rs485_set_mode().

The following defines are available for this function:

  • RS485_MODE_RS485 = 0
  • RS485_MODE_MODBUS_MASTER_RTU = 1
  • RS485_MODE_MODBUS_SLAVE_RTU = 2

Advanced Functions

int rs485_set_communication_led_config(RS485 *rs485, uint8_t config)

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 defines are available for this function:

  • RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
int rs485_get_communication_led_config(RS485 *rs485, uint8_t *ret_config)

Returns the configuration as set by rs485_set_communication_led_config()

The following defines are available for this function:

  • RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
int rs485_set_error_led_config(RS485 *rs485, uint8_t config)

Sets the error LED configuration.

By default the error LED turns on if there is any error (see RS485_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 defines are available for this function:

  • RS485_ERROR_LED_CONFIG_OFF = 0
  • RS485_ERROR_LED_CONFIG_ON = 1
  • RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
int rs485_get_error_led_config(RS485 *rs485, uint8_t *ret_config)

Returns the configuration as set by rs485_set_error_led_config().

The following defines are available for this function:

  • RS485_ERROR_LED_CONFIG_OFF = 0
  • RS485_ERROR_LED_CONFIG_ON = 1
  • RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
int rs485_set_buffer_config(RS485 *rs485, uint16_t send_buffer_size, uint16_t receive_buffer_size)

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

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

The send buffer holds data that was given by rs485_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 rs485_read() or through RS485_CALLBACK_READ callback.

The default configuration is 5120 byte (5kb) per buffer.

int rs485_get_buffer_config(RS485 *rs485, uint16_t *ret_send_buffer_size, uint16_t *ret_receive_buffer_size)

Returns the buffer configuration as set by rs485_set_buffer_config().

int rs485_get_buffer_status(RS485 *rs485, uint16_t *ret_send_buffer_used, uint16_t *ret_receive_buffer_used)

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

See rs485_set_buffer_config() for buffer size configuration.

int rs485_get_error_count(RS485 *rs485, uint32_t *ret_overrun_error_count, uint32_t *ret_parity_error_count)

Returns the current number of overrun and parity errors.

int rs485_get_modbus_common_error_count(RS485 *rs485, uint32_t *ret_timeout_error_count, uint32_t *ret_checksum_error_count, uint32_t *ret_frame_too_big_error_count, uint32_t *ret_illegal_function_error_count, uint32_t *ret_illegal_data_address_error_count, uint32_t *ret_illegal_data_value_error_count, uint32_t *ret_slave_device_failure_error_count)

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.
int rs485_modbus_slave_report_exception(RS485 *rs485, uint8_t request_id, int8_t exception_code)

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 defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
int rs485_modbus_slave_answer_read_coils_request(RS485 *rs485, uint8_t request_id, bool *coils, uint16_t coils_length)

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 RS485_CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_coils(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)

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: Starting address of the read.
  • 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 RS485_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.

int rs485_modbus_slave_answer_read_holding_registers_request(RS485 *rs485, uint8_t request_id, uint16_t *holding_registers, uint16_t holding_registers_length)

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 RS485_CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_holding_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)

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: Starting address of the read.
  • 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 RS485_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.

int rs485_modbus_slave_answer_write_single_coil_request(RS485 *rs485, uint8_t request_id)

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 RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST callback with the Request ID as provided by the arguments of the callback.

int rs485_modbus_master_write_single_coil(RS485 *rs485, uint8_t slave_address, uint32_t coil_address, bool coil_value, uint8_t *ret_request_id)

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: Address of the coil.
  • 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 RS485_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.

int rs485_modbus_slave_answer_write_single_register_request(RS485 *rs485, uint8_t request_id)

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 RS485_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.

int rs485_modbus_master_write_single_register(RS485 *rs485, uint8_t slave_address, uint32_t register_address, uint16_t register_value, uint8_t *ret_request_id)

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

  • Slave Address: Address of the target Modbus slave.
  • Register Address: Address of the register.
  • 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 RS485_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.

int rs485_modbus_slave_answer_write_multiple_coils_request(RS485 *rs485, uint8_t request_id)

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 RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST callback with the Request ID of the callback.

int rs485_modbus_master_write_multiple_coils(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, bool *coils, uint16_t coils_length, uint8_t *ret_request_id)

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: Starting address of the write.

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 RS485_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.

int rs485_modbus_slave_answer_write_multiple_registers_request(RS485 *rs485, uint8_t request_id)

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 RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST callback with the Request ID of the callback.

int rs485_modbus_master_write_multiple_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t *registers, uint16_t registers_length, uint8_t *ret_request_id)

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: Starting Address of the write.

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 RS485_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.

int rs485_modbus_slave_answer_read_discrete_inputs_request(RS485 *rs485, uint8_t request_id, bool *discrete_inputs, uint16_t discrete_inputs_length)

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 RS485_CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_discrete_inputs(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)

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: Starting address of the read.
  • 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 RS485_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.

int rs485_modbus_slave_answer_read_input_registers_request(RS485 *rs485, uint8_t request_id, uint16_t *input_registers, uint16_t input_registers_length)

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 RS485_CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_input_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)

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: Starting address of the read.
  • 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 RS485_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.

int rs485_get_api_version(RS485 *rs485, uint8_t ret_api_version[3])

Returns the version of the API definition (major, minor, revision) 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.

int rs485_get_response_expected(RS485 *rs485, uint8_t function_id, bool *ret_response_expected)

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 rs485_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.

See rs485_set_response_expected() for the list of function ID defines available for this function.

int rs485_set_response_expected(RS485 *rs485, uint8_t function_id, bool response_expected)

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 function ID defines are available for this function:

  • RS485_FUNCTION_ENABLE_READ_CALLBACK = 3
  • RS485_FUNCTION_DISABLE_READ_CALLBACK = 4
  • RS485_FUNCTION_SET_RS485_CONFIGURATION = 6
  • RS485_FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • RS485_FUNCTION_SET_MODE = 10
  • RS485_FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • RS485_FUNCTION_SET_ERROR_LED_CONFIG = 14
  • RS485_FUNCTION_SET_BUFFER_CONFIG = 16
  • RS485_FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • RS485_FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • RS485_FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • RS485_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • RS485_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • RS485_FUNCTION_RESET = 243
  • RS485_FUNCTION_WRITE_UID = 248
int rs485_set_response_expected_all(RS485 *rs485, bool response_expected)

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

int rs485_get_spitfp_error_count(RS485 *rs485, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)

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.

int rs485_set_bootloader_mode(RS485 *rs485, uint8_t mode, uint8_t *ret_status)

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 defines are available for this function:

  • RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • RS485_BOOTLOADER_STATUS_OK = 0
  • RS485_BOOTLOADER_STATUS_INVALID_MODE = 1
  • RS485_BOOTLOADER_STATUS_NO_CHANGE = 2
  • RS485_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • RS485_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • RS485_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int rs485_get_bootloader_mode(RS485 *rs485, uint8_t *ret_mode)

Returns the current bootloader mode, see rs485_set_bootloader_mode().

The following defines are available for this function:

  • RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int rs485_set_write_firmware_pointer(RS485 *rs485, uint32_t pointer)

Sets the firmware pointer for rs485_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.

int rs485_write_firmware(RS485 *rs485, uint8_t data[64], uint8_t *ret_status)

Writes 64 Bytes of firmware at the position as written by rs485_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.

int rs485_set_status_led_config(RS485 *rs485, uint8_t config)

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 defines are available for this function:

  • RS485_STATUS_LED_CONFIG_OFF = 0
  • RS485_STATUS_LED_CONFIG_ON = 1
  • RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs485_get_status_led_config(RS485 *rs485, uint8_t *ret_config)

Returns the configuration as set by rs485_set_status_led_config()

The following defines are available for this function:

  • RS485_STATUS_LED_CONFIG_OFF = 0
  • RS485_STATUS_LED_CONFIG_ON = 1
  • RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs485_get_chip_temperature(RS485 *rs485, int16_t *ret_temperature)

Returns the temperature in °C 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.

int rs485_reset(RS485 *rs485)

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!

int rs485_write_uid(RS485 *rs485, uint32_t uid)

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.

int rs485_read_uid(RS485 *rs485, uint32_t *ret_uid)

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

int rs485_get_identity(RS485 *rs485, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)

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' or 'd'.

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

Callback Configuration Functions

void rs485_register_callback(RS485 *rs485, int16_t callback_id, void *function, void *user_data)

Registers the given function with the given callback_id. The user_data will be passed as the last parameter to the function.

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

int rs485_enable_read_callback(RS485 *rs485)

Enables the RS485_CALLBACK_READ callback.

By default the callback is disabled.

int rs485_disable_read_callback(RS485 *rs485)

Disables the RS485_CALLBACK_READ callback.

By default the callback is disabled.

int rs485_is_read_callback_enabled(RS485 *rs485, bool *ret_enabled)

Returns true if the RS485_CALLBACK_READ callback is enabled, false otherwise.

int rs485_enable_error_count_callback(RS485 *rs485)

Enables the RS485_CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

int rs485_disable_error_count_callback(RS485 *rs485)

Disables the RS485_CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

int rs485_is_error_count_callback_enabled(RS485 *rs485, bool *ret_enabled)

Returns true if the RS485_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 rs485_register_callback() function. The parameters consist of the device object, the callback ID, the callback function and optional user data:

void my_callback(int p, void *user_data) {
    printf("parameter: %d\n", p);
}

rs485_register_callback(&rs485, RS485_CALLBACK_EXAMPLE, (void *)my_callback, NULL);

The available constants with corresponding callback function signatures 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.

RS485_CALLBACK_READ
void callback(char *message, uint16_t message_length, void *user_data)

This callback is called if new data is available.

To enable this callback, use rs485_enable_read_callback().

RS485_CALLBACK_ERROR_COUNT
void callback(uint32_t overrun_error_count, uint32_t parity_error_count, void *user_data)

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

RS485_CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)

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 starting address and the number of coils to be read as received by the request.

To send a response of this request use rs485_modbus_slave_answer_read_coils_request().

RS485_CALLBACK_MODBUS_MASTER_READ_COILS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, bool *coils, uint16_t coils_length, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)

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 starting address and the number of holding registers to be read as received by the request.

To send a response of this request use rs485_modbus_slave_answer_read_holding_registers_request().

RS485_CALLBACK_MODBUS_MASTER_READ_HOLDING_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, uint16_t *holding_registers, uint16_t holding_registers_length, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST
void callback(uint8_t request_id, uint32_t coil_address, bool coil_value, void *user_data)

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 coil address and the value of coil to be written as received by the request.

To send a response of this request use rs485_modbus_slave_answer_write_single_coil_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_COIL_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST
void callback(uint8_t request_id, uint32_t register_address, uint16_t register_value, void *user_data)

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single register. The parameters are request ID of the request, the register address and the register value to be written as received by the request.

To send a response of this request use rs485_modbus_slave_answer_write_single_register_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, bool *coils, uint16_t coils_length, void *user_data)

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 starting address and the data to be written as received by the request.

To send a response of this request use rs485_modbus_slave_answer_write_multiple_coils_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_COILS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t *registers, uint16_t registers_length, void *user_data)

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple registers. The parameters are request ID of the request, the starting address and the data to be written as received by the request.

To send a response of this request use rs485_modbus_slave_answer_write_multiple_registers_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)

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 starting address and the number of discrete inputs to be read as received by the request.

To send a response of this request use rs485_modbus_slave_answer_read_discrete_inputs_request().

RS485_CALLBACK_MODBUS_MASTER_READ_DISCRETE_INPUTS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, bool *discrete_inputs, uint16_t discrete_inputs_length, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)

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 starting address and the number of input registers to be read as received by the request.

To send a response of this request use rs485_modbus_slave_answer_read_input_registers_request().

RS485_CALLBACK_MODBUS_MASTER_READ_INPUT_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, uint16_t *input_registers, uint16_t input_registers_length, void *user_data)

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 zero then the number represents a Modbus exception code. If it is less than zero 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 rs485_set_modbus_configuration().

The following defines are available for this function:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11

Constants

RS485_DEVICE_IDENTIFIER

This constant is used to identify a RS485 Bricklet.

The rs485_get_identity() function and the IPCON_CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

RS485_DEVICE_DISPLAY_NAME

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