AutomationDirect C0-USER-M Manual page 263

Chapter 4: PLC Communications
Exception Response (Exception Code)
When the slave CLICK PLC receives a request from the Modbus master that it cannot respond
to, the slave CLICK PLC sends an exception response to the Modbus master. The CLICK
PLC supports the following Exception Responses.
Code
01
02
03
04
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CLICK PLC Hardware User Manual, 6th Edition, Rev. F – C0-USER-M
Exception Response (Exception Code)
Name
The CLICK PLC does not support the function code received from the MODBUS
Illegal Function
master.
Illegal Data Address The MODBUS master tried to access to an invalid address.
The data length is zero or exceeds the maximum size.
Illegal Data Value The data for Write Single Coil is not FF00h (ON) or 0000h (OFF).
The PLC mode change request from the MODBUS master is not valid.
Password is locked.
When the PLC mode switch is in STOP position, the MODBUS master
Slave Device Failure requested to switch to RUN mode.
When the PLC mode switch is in RUN position, the MODBUS master requested
to switch to the Firmware Update mode.
Details of Exception Response