Compact Logix and Modbus ascii

Hi all,
Hopefully this is a simple one. Need to communicate with a third party PID controller via RS 485 with modbus ascii/RTU. Is this just a matter of buying a converter from 232 to 485 and sending ascii strings to the PID contoller? This would use the serial port on the PLC processor. Or do I need to purchase a seperate module for this? We are using a compact logix L35E. We need to send the controller a new setpoint ever so often and we would need to pole it for a temperature reading. I seem to remember a long time ago I was able to do this using a mitsu PLC but my memory is running out of room and I have had to dump some stuff .
Thanks for the help!
stoop

A bit harder than that. You either need to buy a 3rd party module (can,t remember who makes them but they are not cheap) or download a program file from the Rockwell samples website that will allow the serial port to be used for modbus.
Regards Alan

CompactLogix - Modbus Solutions

You have a couple of options.
1. As stated by Alan Case can be found at http://www.ab.com/go/iatools. Click on the Beyond Getting Started tab. Select Sample Code Library website. Once at the sample code page, go to the category Technologies and Functionalities and select Communication Protocol. Execute the search and you will find the code sample there.

2. Prosoft makes a module that can be used with the CompactLogix to facilitate modbus comms. The catalog number is MVI69-MCM. Follow this link for more details:

http://www.psft.com/content/view/full/6058

I used one of the Prosoft MVI69-MCM modules to communicate with a Pneumercator tank monitor. I expected to spend a day struggling with it but it worked first time. The module comes c/w software ready to suck into your project.
I can't say enough about their support group.

Thanks guys this was a big help!

I suggest that you use this:

http://www.ab.com/drives/22-comm/1769-sm2/index.html

It's pretty easy to set up.