6-12
469 Motor Management Relay
GE Power Management
6.2 SUPPORTED MODBUS FUNCTIONS
6 COMMUNICATIONS
6
6.2.7 FUNCTION CODE 08: LOOPBACK TEST
Modbus Implementation:
Loopback Test
469 Implementation:
Loopback Test
This function is used to test the integrity of the communication link. The 469 will echo the request.
MESSAGE FORMAT AND EXAMPLE
Loopback test from slave 11.
MASTER TRANSMISSION:
BYTES
EXAMPLE / DESCRIPTION
SLAVE ADDRESS
1
0B
message for slave 11
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 A1
CRC calculated by the master
SLAVE RESPONSE:
BYTES
EXAMPLE / DESCRIPTION
SLAVE ADDRESS
1
0B
response message from slave 11
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 A1
CRC calculated by the slave