modbus communication in CVI

[Dwivedi]

I have an assignment of developing a module that can make the application communicate with a Device Controller, using the MODBUS protocol.
I have tried the sample code available with the NI LabWindows/CVI/Sample.prj. But I have been unable to read back anything from the controller.
Can someone suggest me some basics for this problem. How should I code the program so that it reads back from the Device.
Any suggestions or sample codes would be helpful.

Dwivedi

[Russell_G.]

How are you communicating with the device? Is it serially? Do you have the correct driver installed for the device that you are trying to communicate with? Here is a link that may help.

Here is another >link that may help in troubleshooting your communication problem. Although it deals with LabVIEW, the same ideas apply to CVI.

Russell G.
NI Applications Engineer