Modbus and Control Logix - setup and use

I'm an experienced PLC SLC programmer. I've been using Cotnrol Logix for about 2 years now and have quite a few programs out in the field. I have recently been tasked with setting up Modbus using Prosoft MVI56-MCM and MVI56-MNET modules.

In the SLC's you setup the programming with the canned rungs from ProSoft. You then transfer your data to a range of Integer files for the write to modbus and setup read files for the information coming back to you.

I've been told that the CLX setup is different as the communications are setup in the ProSoft card and the Master can access whatever tags it needs. This does not sound correct to me, but like I said - I'm new at Modbus Comms.

Pointers would be great. A ahort sample program would be great. I can get the thrust of the concept and move on if there are any magicians with modbus out there!

Thanks for taking a shot.

The MVI Modbus modules (1746, 1756, 1794, 1771) work very similarly, and are in turn very similar to the older 3150 series modules.

The example code from the Prosoft website is really good. They have also recently offered the example code as Add-On Instructions for v16+ of RSLogix 5000.

Call the Prosoft help line. I found them great when I had to use that module for the first time. I expected to spend a day at least struggling but lo and behold it worked first time.
Roy