GE Multilin G650, Manual

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B-6 G650 Generator Protection & Control System GEK-113285A
B.2 MODBUS G650 APPENDIX B
B
B.2.6 FUNCTION CODES
B.2.7 EXCEPTIONS AND ERROR RESPONDS
The following table shows error codes defined in ModBus protocol:
CODE MODBUS
NAME G650
DEFINITION COMMENT
HEX DEC
03 3 Read Holding
Registers
Reading of any
value
Any of these two functions allow the master to read 1 or more consecutive relay
addresses. Registers are always 16-bit long with the most important byte first. The
maximum number of registers that can be read in a single package is 125, equivalent
to 250 bytes.
04 4 Read Input
Registers
Reading of any
value
10 16 Preset Multiple
Registers
Writing This function allows writing 1 or more registers representing one or more settings.
Registers are 2-byte long values, transmitted with the most important byte first. The
maximum number of registers to be written in a single package is 125.
01 ILLEGAL FUNCTION The slave does not support any function with the received function code in this message.
02 ILLEGAL DATA ADDRESS Master is trying to perform an operation in an incorrect address.
03 ILLEGAL DATA VALUE Slave has detected that the value sent by the master is not valid.
04 ILLEGAL RESPONSE LENGTH Indicates that a response to the master’s request would exceed the maximum specified size for
that function code.
05 ACKNOWLEDGE Generic acknowledgement.
06 SLAVE DEVICE BUSY Slave is busy and cannot perform the requested operation.
07 NEGATIVE ACKNOWLEDGE Negative acknowledgement.