Modbus Comms with AB L32E

Ok Here goes, I have an Allen Bradley Micro LOgix L32E that I am trying to get communicating via Modbus over channel 0

I am a little confused as I have never tried this before I am using the Sample program Modbusmaster.acd that is provided with the software I have also downloaded the documentation that comes with the sample program. My question is this when configuring the parameters for channel 0, what does the system protocol ned to be set to. I feel like I have a handle on the logic portion and the Baldor Drives I am trying to communicate with seem to be configured properly according to the manufacturer. I am banging my head against the wall trying to get this working any advice will be welcomed

Thank you

Do you mean a Compactlogix L32E? I think you need the SM2 card to talk Modbus.

I haven't heard of a way to do it through the CH0 port...

I ran into another fella who was trying to do the same thing. He had the example code as well and we never could get it to work. We ended up using a data converter to go from Modbus 485 to the AB via the DF1 or Ethernet port.

Joe_WaZoo

With the sample code you can use the comport. It's easier with the SM2 card though, that's what I use.
Prosoft also makes a card for this.

I have seen the sample code. Not sure if it works that well. When you have a look at the code it seems in my opinion to be poorly written. (seemed to have blocked out bits of code that were not used, poorly documented etc) One day I have always wanted to re-write it, make it into an AOI then post it back on the sample website. Never had the time and probably if I did the next week there would be a release of compact logix where the comm port supported modbus natively.
Regards Alan Case

Disclosure: I don't like this implementation of Modbus on the Logix controller and very much prefer Prosoft cards.

There is actually a user manual that goes with that sample code which includes screenshots of things like the User Mode configuration of the serial port.

http://literature.rockwellautomation.com/idc/groups/literature/documents/ap/cig-ap129_-en-p.pdf

The 2.0 version of the Modbus master and slave code is in the RA Knowledgebase document 42662. I tested this code in a 1756-L1 v13 controller just last week.

To troubleshoot, the first question is: Is the Channel 0 communication LED on the controller flashing ? If so, you can use a serial analyzer to help diagnose the problem.

If not, you're going to have to send somebody, either the forum or RA Tech Support, your code and an explanation of which registers on which slave devices you intend to read and write.

To the above, i have only seen version 1 of the code.
Regards Alan Case

I used the Prosoft card. The card comes with AB logic example that you can import directly into your configuration. The technical support from Prosoft is second to none. Much to my amazement the card worked first time.
Roy

I second Ken's opinion. Use the Prosoft card or some other protocol converter device to get Modbus comms into the L32 PLC.

Joe_WaZoo