GE Industrial Solutions Record Plus FG600 SMR2 Modbus - Manual (Page 8)

SMR2 Modbus User Manual
5
Addres
s
(1
byte)
Code
(1 byte)
Previous transmitted
data (2 bytes)
64h 38h xxh xxh xxh xxh xxh
xxh xxh xxh xxh
CRCl
CRCh
Exception Response
If the slave receives a message without a
communications error, but is unable to process it, the
slave will return an exception response to inform the
master of the error. The high order bit will be set in
the function code and returned with the characterizing
exception response code:
01h - Invalid Function Code
The Function Code is not recognized or defined by the
SMR2.
02h - Invalid register
The Register address is not recognized or defined by
the SMR2
05h – Acknowledge
The SMR2 has accepted the request and is processing
it, but a long duration of time will be required to do so.
This response is returned to prevent a timeout error
from occurring in the master.
06h - Slave busy
The SMR2 is busy processing a long duration
command. The master should retransmit the message
latter when the slave is free.
84h - Partial register access error
Command reads or writes to a register that represents
only part of the SMR2 register address. The multiple
register addresses must be read or written together.
Example: Long Time SOS consumes 2 register
addresses, thus both must be read together.
85h - Write protect violation
Command writes to a valid Register, which is defined as
Read Only.
88h - Invalid coil
The Coil address is not recognized or defined by the
SMR2.
Function Codes
The Modbus functions listed in below are supported:
Function
Code
Command Purpose Register Group
03 Read Holding Registers Reading the setpoint
registers Setpoint registers, Fixed value registers
04 Read Input Registers Reading actual value
registers
Actual value registers and event registers
05 Force Single Coil Setting the signal coil or
executing single
command
Command coils
06 Preset Single Register Write Data into single
Register Setpoint registers, Fixed value registers
16
10 hex
Preset Multiple Registers Write Data into multiple
Registers
Setpoint registers, Fixed value registers
56 Retransmit last message Retransmit last message N/A