libmodbus/doc/modbus_report_slave_id.txt

modbus_report_slave_id(3)
=========================


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
-------
[source,c]
-------------------
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>