Function Code 07H - GE 350 Communications Manual

FUNCTION CODE 07H

Function Code 07H
8-10
Modbus Implementation: Read Exception Status
3 Series relay Implementation: Read Device Status
This is a function used to quickly read the status of a selected device. A short message
length allows for rapid reading of status. The status byte returned will have individual bits
set to 1 or 0 depending on the status of the slave device. For this example, consider the
following 3 Series relay general status byte:
The master/slave packets have the following format:
Table 8-5: Function code 7 bitmask
Bit
0
1
2
3
4
5
6
7
Table 8-6: 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
Query:
Field Name
Slave Address
Function
Response:
Field Name
Slave Address
Function
Device Status (see definition above)
Function
Alarm
Trip
Self Test
Breaker Connected
52a Contact
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
Hex
FE
07
Hex
FE
07
2C
SR3 SERIES PROTECTIVE RELAY PLATFORM – COMMUNICATIONS GUIDE
CHAPTER 8: MODBUS FUNCTIONS
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