07: Read Device Status - GE 239 Instruction Manual

7 COMMUNICATIONS
• Modbus Implementation:Read Exception Status
• 239 Implementation:
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.
239 General Status Byte:
LSBit B0: Alarm condition = 1
B1: Trip condition = 1
B2: Internal fault = 1
B3: Not used
B4: Not used
B5: Not used
B6: Not used
MSBit B7: Not used
a) MESSAGE FORMAT AND EXAMPLE
Request status from slave 11.
Master Transmission
SLAVE ADDRESS
FUNCTION CODE
CRC
Slave Response
SLAVE ADDRESS
FUNCTION CODE
DEVICE STATUS
CRC
GE Multilin
Courtesy of NationalSwitchgear.com
Read Device Status
Bytes
- 1 byte
- 1 byte
- 2 bytes
Bytes
- 1 byte
- 1 byte
- 1 byte
- 2 bytes
239 Motor Protection Relay
7 COMMUNICATIONS

7.11 07: READ DEVICE STATUS

Example (hex)
11 message for slave 11
07 read device status
8F CRC calculated by the master
BB
Example (hex)
11 message from slave 11
07 execute operation
00 status = 00000000 in binary
23 CRC calculated by slave
F5
7
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