GE 489 Communications Guide

489 GENERATOR MANAGEMENT RELAY – COMMUNICATIONS GUIDE 7
Message Format and Example:
Request slave 11 to store the value 01F4 in Setpoint address 1180. After the transmission
in this example is complete, Setpoints address 1180 will contain the value 01F4.
CG.2.5 Function Code 07: Read Device Status
Modbus Implementation: Read Exception Status
489 Implementation: Read Device Status
This function reads the selected device status. A short message length allows for rapid
reading of status. The returned status byte has individual bits set to 1 or 0 depending on
the slave device status. The 489 general status byte is shown below:
Note that if the generator status is neither Offline nor Online, the generator status is
Tripped.
Message Format and Example:
Request status from slave 11.
Master Transmission Bytes Example Description
Slave Address 1 0B message for slave 11
Function Code 1 06 store single setpoint
Data Starting Address 2 11 80 setpoint address 1180h
Data 2 01 F4 data for address 1180h
CRC (low, high) 2 8D A3 computed CRC error code
Slave Response Bytes Example Description
Slave Address 1 0B message from slave 11
Function Code 1 06 store single setpoint
Data Starting Address 2 11 80 setpoint address 1180h
Data 2 01 F4 data for address 1180h
CRC (low, high) 2 8D A3 computed CRC error code
Bit Description Bit Description
B0 1 TRIP relay operated = 1 B4 5 ALARM relay operated = 1
B1 2 AUXILIARY relay operated = 1 B5 6 SERVICE relay operated = 1
B2 3 AUXILIARY relay operated = 1 B6 Offline = 1
B3 4 AUXILIARY relay operated = 1 B7 Online = 1
Master Transmission Bytes Example Description
Slave Address 1 0B message for slave 11
Function Code 1 07 read device status
CRC (low, high) 2 47 42 computed CRC error code
Slave Response Bytes Example Description
Slave Address 1 0B message from slave 11
Function Code 1 07 read device status
Device Status 1 59 status = 01011001b

GE 489 Specifications

General

Brand	GE
Model	489
Category	Relays
Language	English