Modbus exception error

[I_I]

Hello All,

I am trying to configure BTC controller using NIModbus.dll. But I am getting Modbus exception error 6001 and I am not able to resolve it.I saw all same settings are good working for Eurotherm controller.

Let me know anybody can help.

[Robert M]

I apologize for the delay in responding. 

Is LabVIEW acting as the master or slave in your setup?  My guess is slave.  Error 6001 correlates to Modbus exception code 01 (subtract the 6000) as is defined in the Modbus spec as "Illegal Function" with the following explanation:

The function code received in the query is not an allowable action for the server (or slave). This may be because the function code is only applicable to newer devices, and was not implemented in the unit selected. It could also indicate that the server (or slave) is in the wrong state to process a request of this type, for example because it is unconfigured and is being asked to return register values.

My guess is that your device, acting as master, is sending a function to LabVIEW (acting as slave) that LabVIEW does not recognize.  LabVIEW supports class 0 and class 1 functions.  Your device is probably sending a function from a higher level class.

Hope this helps,

[dsss]

Where can I find what functions are class 0 1,2, etc?