Hi,

I am trying to get Compact logix communicating over a mb1 driver. Right now I am just trying to wrap my head around the sample program for modbus slave. I dont have the controller yet so I can not do any testing. My big question now is how is the data stored in logix. If I have tag with the address 40001 does that refer to Mod_DataHoldReg4[1]. I know it would be easier to use the prosoft card but my boss thinks it might be worth while to try and use this program. So if anyone has used this before please let me know. Your help would be greatly appreciated
Thanks

Are you using the MB1 driver used with Intellution products (iFix..)?

If thats the case, then you wont be able to communicate with the Compact Logix platform.

This is because the Logix platform does not have direct memory address as in other PLCs.

For instance, your tag Mod_DataHoldReg4[1] refers to a memory location in the PLC memory and it will not point to 40001. The Logix platform uses the PLC memory as C or VB would use it.

A tag defined in Logix is used directly and its memeory address is not.

So, you wont be able to address the memory locations in CompactLogix using something like MB1.

One way to do it is OPC. Use any OPC server/client like Topserver or IGS (over TCP/IP, for which you will need the L32E or L35E processors). Hook it up with the RSLinx OPC server to fetch and send data. This way you can use to communicate CompactLogix with SCADA or any other OPC compatible product. This will save you the Prosoft card, but you will have to invest in OPC.

We did not want to put in a new opc server. If you look in the logix projects folder there are sample programs to get logix to communicate over modbus via serial port. I get most of the program. Execpt how the data is stored and transfered. And this affects how lay out my tag structure in logix.