Exception Response for MODBUS

Topic: CL142

Description

When the CLICK PLC is used as a MODBUSSlave and could not handle the message from the MODBUS Master, it returns an Exception Response (Exception Code) to the MODBUS Master.

Exception Response (Exception Code)

The CLICK PLC supports the following Exception Responses.

 

Code

Name

Meaning

 

01

Illegal Function

  • The CLICK PLC does not support the function code received from the MODBUS Master.

 

02

Illegal Data Address

  • The MODBUS Master tried to access to an invalid Address.

 

 

03

Illegal Data Value

  • The Data Length is Zero or exceeds the maximum size.

  • 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.

 

 

04

Slave Device Failure

  • Password is locked.

  • When the PLC mode switch is in the STOP position, the MODBUS Master requested to switch to RUN mode.

  • When the PLC mode switch is in the RUN position, the MODBUS Master requested to switch to the Firmware Update mode.