GE Power Management
MM2 Motor Manager 2 6-11
6 COMMUNICATIONS 6.2 MODBUS FUNCTIONS
6
6.2.7 FUNCTION CODE 08H
Modbus Implementation: Loopback Test
MM2 Implementation: Loopback Test
This function is used to test the integrity of the communication link. The MM2 will echo the request.
For example, consider a loopback test from slave 17:
Table 6–7: 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