GE SPM Series, Instruction Manual

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GE Power Management SPM Synchronous Motor Protection & Control 9-
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9 MODBUS COMMUNICATIONS 9.1 IMPLEMENTATION
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9 MODBUS COMMUNICATIONS 9.1 IMPLEMENTATION 9.1.1 MODBUS PROTOCOL
The SPM supports a subset of the AEG Modicon Modbus RTU serial communication standard using a 2-wire
RS485 interface. The following commands are supported (Modbus names are in brackets):
• 03: Read Setpoints and Actual Values (read holding registers)
• 04: Read Setpoints and Actual Values (read input registers)
• 05: Execute Operation (force single coil; coil number 1 emulates the relay reset function)
• 06: Store Single Setpoint (preset single register)
• 07: Read Device Status (read exception status)
• 16: Store Multiple Setpoints (preset multiple registers)
9.1.2 PERFORMANCE REQUIREMENTS
• Baud rates: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200.
• Turn around time less than 50 ms from receipt of last character to transmission of first character.
• Two-wire RS485 connection.
• Data frame fixed at 1 start, 8 data and 1 stop bit.
9.1.3 SETPOINTS
The following setpoints are required to set up the Modbus communications port:
CONFIGURATIONS \ RTU ADDRESS :Range 1 to 254. Set to the SPM address
(must be unique for each relay on the channel).
CONFIGURATIONS \ BAUD RATE : Set from 300 to 115k baud
CONFIGURATIONS \ PARITY : Set to none, even or odd, depending on configuration
CONFIGURATIONS \ TURNAROUND : Enter the minimum Modbus turnaround time, 0 to 1000 ms
9.1.4 EXECUTE OPERATION COMMAND CODES (COIL NUMBERS)
The following table lists the coil numbers, which may be used in the Modbus "force coil" command.
Table 9–1: EXECUTE OPERATION CODES
COIL NUMBER FUNCTION
0001h Simulate a keypad reset (i.e., reset a trip after the condition has cleared)
0101h Force the FAR into the energized state
0111h Force the FAR into the de-energized state
0121h Un-force the FAR, reverting it to program control
0102h Force the FCX relay into the energized state
0112h Force the FCX relay into the de-energized state
0122h Un-force the FCX relay, reverting it to program control
0103h Force the TRP relay into the energized state
0113h Force the TRP relay into the de-energized state
0123h Un-force the TRP relay, reverting it to program control