bionic (3) modbus_report_slave_id.3.gz

NAME

       modbus_report_slave_id - returns a description of the controller

SYNOPSIS

       int modbus_report_slave_id(modbus_t *ctx, uint8_t *dest);

DESCRIPTION

       The modbus_report_slave_id() function shall send a request to the controller to obtain a description of
       the controller.

       The response stored in dest contains:

       •   the byte count of the response

       •   the slave ID, this unique ID is in reality not unique at all so it’s not possible to depend on it to
           know how the information are packed in the response.

       •   the run indicator status (0x00 = OFF, 0xFF = ON)

       •   additional data specific to each controller. For example, libmodbus returns the version of the
           library as a string.

RETURN VALUE

       The modbus_report_slave_id() function shall return the number of read data if successful. Otherwise it
       shall return -1 and set errno.

EXAMPLE

           uint8_t *tab_bytes;

           ...

           rc = modbus_report_slave_id(ctx, tab_bytes);
           if (rc > 1) {
               printf("Run Status Indicator: %s\n", tab_bytes[1] ? "ON" : "OFF");
           }

AUTHORS

       The libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com[1]>

NOTES

        1. stephane.raimbault@gmail.com
           mailto:stephane.raimbault@gmail.com