GE 489 Communications Manual page 10

CG.2.3 Function Code 05: Execute Operation
CG.2.4 Function Code 06: Store Single Setpoint
6
Master Transmission
CRC (low, high)
Slave Response
Slave Address
Function Code
Byte Count
Data #1 (high, low)
Data #2 (high, low)
CRC (low, high)
Modbus Implementation: Force Single Coil
489 Implementation: Execute Operation
This function code allows the master to request specific 489 command operations. The
command numbers listed in the Commands area of the memory map correspond to
operation code for function code 05. The operation commands can also be initiated by
writing to the Commands area of the memory map using function code 16. Refer to
Section CG.2.7 Function Code 16: Store Multiple Setpoints on page –8 for complete details.
Supported Operations:Reset 489 (operation code 1); Generator Start (operation code 2);
Generator Stop (operation code 3); Waveform Trigger (operation code 4)
Message Format and Example:
Reset 489 (operation code 1).
Master Transmission
Slave Address
Function Code
Operation Code
Code Value
CRC (low, high)
Slave Response
Slave Address
Function Code
Operation Code
Code Value
CRC (low, high)
Modbus Implementation: Preset Single Register
489 Implementation: Store Single Setpoint
This command allows the master to store a single setpoint into the 489 memory. The slave
response to this function code is to echo the entire master transmission.
Bytes Example
2 D5 17 computed CRC error code
Bytes Example
1 0B message from slave 11
1 03 read register values
1 04 2 registers = 4 bytes total
2 00 64 value in address 0235h
2 00 0A value in address 0236h
2 EB 91 computed CRC error code
Bytes Example
1 0B message for slave 11
1 05 execute operation
2 00 01 reset command (op code 1)
2 FF 00 perform function
2 DD 50 computed CRC error code
Bytes Example
1 0B message from slave 11
1 05 execute operation
2 00 01 reset command (op code 1)
2 FF 00 perform function
2 DD 50 computed CRC error code
489 GENERATOR MANAGEMENT RELAY – COMMUNICATIONS GUIDE
Description
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