Ethernet IP Testing

Hello,

I currently am using an activex control (Allen Bradley Studio 5.0) from Ingear to read and write tags over ethernet to customer PLCs, which has been working fine for some time across multiple customers.

However, a single customer is having some communication issues - so I would to do some local testing, but I don't have a PLC in house. So my question is:

Are there any emulators or software that would allow me to fake a PLC (and retain tag support)? Or is the only way to do this is by purchasing softlogix or a real PLC, plus the programming software? Obviously I am looking at the cheapest (or free-est) alternative, but am willing to spend money if thats what it takes.

Thank you!
-Chris

Which AB PLC?

A controllogix 1756 system.

KJ Contracting http://www.usedallenbradley.com/index.htm can set you up with used AB equipment at relatively low cost and they are located close to you. They have some software but I don't know about RSLogix 5000.

Steve.

What sort of "issues" are you having ?

While an RSLogix 5000 Emulate instance with an EtherNet/IP module in the virtual backplane would be logically identical to a 1756-ENBT and a ControlLogix, it uses the Windows TCP/IP stack and the resources of your PC, so from a performance or bug testing perspective it's very different.

I always try to use hardware for performance testing, preferably hardware from the same hardware Series and matching firmware revisions.

Steve, that is good to know. Thank you.

Ken, there are a few things I would like to test that are not speed sensitive (such as reading/writing tags), so I assume by your response the RSLogix emulator would work.

Ultimately I'm looking to test the speed of the communication, the tcp socket connection times as that is where the issues lie. It looks like spending the $$$ on a PLC & software is the only way to be sure of the results.

I *was* hoping there might be a cheap / free 3rd party emulator (that has ethernet and tag support available) so I could get started on the first round of tests before purchasing a PLC, but I guess nothing will be as exact as a physical PLC in the long run.

Like Ken asked, a little more description on the issue would be helpful. Since so many things can be different from system to system, I would start looking at what is different with this customer than other projects. Some things that I would want to know would be things like:

• Does problem system have ethernet I/O?
• Do other systems have ethernet I/O?
• Is the switch managed or unmanaged? (on managed cisco switches I have seen misconfigurations cause communication loss and issues on heavily loaded Ethernet i/o systems for NOT using a managed switch)
• What is the firmware rev in the ethernet module?
• Is there a lot of messaging in the problem program that is not in other systems?

AB also has a monitoring tool (Logix5000 Task Monitor) that can look at ControlLogix processor utilization and also the processor utilization of the Ethernet module. It will also let you know if there are issues with the resources available in the Ethernet module.

Darren

Just my 2 cents but start off with the cables. I just got finished a job were I had to go around and fix every connection the electrician made for Ethernet, sometime my Ethernet IO and HMI would talk and othertimes no go, it was the cables.

Good point. Many times it is the simple stuff. I tend to jump to much to the complex items first.

Darren

The customer issue is that the occasional slow PLC communication causes our (single threaded) app to stop and wait, and miss some digital i/o events.

I secured some test time with a real PLC, and found everything behaved well with a clean environment on a network with little traffic.

It is difficult to troubleshoot, as it could be the PLC or network which we do not control. This site does have more connected to the PLC then any other site we have.

The next step is to take the findings here and head to the customers site and try to clean up their system and traffic, and isolate our system as much as possible. I'd like to check out the task monitoring tool while onsite to see how the ethernet card is doing.

Thank you all for your help and ideas.

When you go I would download and take the latest copy of Wireshark. Hopefully they have a switch you can do port mirroring on so you can monitor the network traffic.


http://www.wireshark.org/


Darren