MODBUS_REPORT_SLAVE_(3) Libmodbus Manual MODBUS_REPORT_SLAVE_(3)NAMEmodbus_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
libmodbus 3.1.0 10/06/2013 MODBUS_REPORT_SLAVE_(3)
