GE Power Quality Meter Series

GE Power Management PQM Power Quality Meter 7-9
7 MODBUS COMMUNICATIONS 7.2 MODBUS FUNCTIONS
7
7.2.7 FUNCTION CODE 08 – LOOPBACK TEST
Modbus Implementation
: Loopback Test
PQM Implementation
: Loopback Test
This function is used to test the integrity of the communication link. The PQM will echo the request.
MESSAGE FORMAT AND EXAMPLE:
Loopback test from slave 11.
Table 7–6: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 08H
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave 17
FUNCTION CODE 1 08 loopback test
DIAG CODE 2 00 00 must be 00 00
DATA 2 00 00 must be 00 00
CRC 2 E0 0B CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from slave 17
FUNCTION CODE 1 08 loopback test
DIAG CODE 2 00 00 must be 00 00
DATA 2 00 00 must be 00 00
CRC 2 E0 0B CRC error code