GE 239

GE Multilin 239 Motor Protection Relay 7-7
7 COMMUNICATIONS 7 COMMUNICATIONS
7
7.11 07: READ DEVICE STATUS
• Modbus Implementation:Read Exception Status
• 239 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.
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 Bytes Example (hex)
SLAVE ADDRESS - 1 byte 11 message for slave 11
FUNCTION CODE - 1 byte 07 read device status
CRC - 2 bytes 8F CRC calculated by the master
BB
Slave Response Bytes Example (hex)
SLAVE ADDRESS - 1 byte 11 message from slave 11
FUNCTION CODE - 1 byte 07 execute operation
DEVICE STATUS - 1 byte 00 status = 00000000 in binary
CRC - 2 bytes 23 CRC calculated by slave
F5