Function Code 08H - GE 350 Communications Manual

CHAPTER 9: MODBUS FUNCTIONS

Function Code 08H

350 FEEDER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
Bit
5
6
7
Table 9-6: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 07H
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
DEVICE STATUS (see definition
above)
CRC
Modbus Implementation: Loopback
Test 350 Implementation: Loopback Test
This function is used to test the integrity of the communication link. The 350 will echo the
request.
For example, consider a loopback test from slave 17:
Table 9-7: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 08H
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
DIAG CODE
DATA
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
DIAG CODE
DATA
CRC
Function
52b Contact
Maintenance
Relay in Service
BYTES EXAMPLE
1 11
1 07
2 4C 22
BYTES EXAMPLE
1 11
1 07
1 2C
2 22 28
BYTES EXAMPLE
1 11
1 08
2 00 00
2 00 00
2 E0 0B
BYTES EXAMPLE
1 11
1 08
2 00 00
2 00 00
2 E0 0B
FUNCTION CODE 08H
DESCRIPTION
message for slave 17
read device status
CRC error code
DESCRIPTION
message from slave
17
read device status
status = 00101100
(in binary)
CRC error code
DESCRIPTION
message for slave 17
loopback test
must be 00 00
must be 00 00
CRC error code
DESCRIPTION
message from slave
17
loopback test
must be 00 00
must be 00 00
CRC error code
9–5