1756-EN2T Comms issue

I have just installed a new rack in the process and having problems going online through our EN2T card. I have used these cards in the past with no problems so I think I have it set up right. I can see it in RSLinx, but when I try to go online through my program it tells me it cant go online and cant communicate with RSlinx. For trouble shooting purposes I put in a ENBT card and it works fine. I can leave the ENBT card in I suppose but cant understand why the other one does not work. Can anyone shed some light on this for me?? And before anyone asks I have tried two different EN2T cards with the same result so I know I don't have a bad card.

Are these cards different hardware/firmware revisions?

Can you browse to its configuration page in Explorer or Chrome and view the configuration?

If I remember right, the ENBT is configured with the wheels but you have to configure the EN2T through Linx or BOOTP.

But check your config on the diagnostics page first. If you can't get to that then that tells you something too.

JohnCalderwood said:

Are these cards different hardware/firmware revisions?

Click to expand...

Yes they are, 10.7 and 6.1. I have had these cards work even if the card revision and program revisions are different.

scarince said:

Can you browse to its configuration page in Explorer or Chrome and view the configuration?

If I remember right, the ENBT is configured with the wheels but you have to configure the EN2T through Linx or BOOTP.

But check your config on the diagnostics page first. If you can't get to that then that tells you something too.

Click to expand...

EN2T has the wheels and ENBT is BOOTP. I can get to the config through linx.

Newer firmware version on EN2T may require newest version of RSLinx.
Install latest RSLinx version and try again.

GTUnit said:

Newer firmware version on EN2T may require newest version of RSLinx.
Install latest RSLinx version and try again.

Click to expand...

I do have the latest version.

Try putting both cards in the rack and browsing from the ENBT to the EN2T through the backplane. If the EN2T shows up in RsLinx, right click and view the configuration and set up.

Aut0m8n said:

Try putting both cards in the rack and browsing from the ENBT to the EN2T through the backplane. If the EN2T shows up in RsLinx, right click and view the configuration and set up.

Click to expand...

I have done that. What should I be looking for in configuration?

So, I inhibited all my I/O modules and then I could go online with the controller. I un inhibited each module one at a time until it kicked me offline. Narrowed it down to the AC out cards. Called Rockwell and apparently it is a scan time issue. Because I have nothing really in the way of logic in my program yet, it was scanning through to fast. Rule of thumb is to have the scan time above 1ms. All I had to do as a temporary fix to stay online was change my main program from continuous to periodic. Never heard of that before but it worked. Not sure why I could stay online with the ENBT card versus the EN2t. Forgot to ask them that question.

I've never heard of that either!

Thanks so much for letting us know....I never would have guessed that.

Oh, wow, I wouldn't have thought of that either.

If this is the issue I'm thinking of, it was a problem specific to an empty or very small Program in the Continuous Task, along with a certain number of AC or Diagnostic output modules.

It's described in the RA Knowledgebase:

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/467702/page/2

The problem may run deeper...

More fuel for the fire. I've had a similar issue with three separate new systems in the last 6 months. All L72 processors, v20, all with ENBT and EN2T, two with EN3TR.

Doing checkout in the panelshop I couldn't stay connected online with the PLC through the EN2Ts or EN3TRs. I don't remember if I tried the ENBT. I could always connect to the PLC with RSLogix5k, but would get kicked offline within a few minutes. I figured it was something goofy with my Win7 or RSLinx. I ended up using the USB port, which worked great except the short USB cable.

Once the first two panels were installed at the factory the problem seemed to go away with those two. I could connect via the EN2Ts and the ENBT. I had made no changes to my PC software, so now I didn't know what to think.

I'm now working on the third system. The first 4 weeks at the factory I could connect via the EN2Ts. Starting last week I was getting kicked offline within 30-90 seconds of going online. I also noticed that using FTVS "Test Application" I would lose PLC comm for a few seconds, then it would re-establish. This happened at the same time I got kicked offline with RSLogix5k. So now that's bringing in RSLinx Enterprise too, I am starting to think maybe it is in the PLC. I used USB for a while, then we got the ENBT network up and going this week and I tried that - it worked. "Test Application" is still using the EN2T and still loses comm.

So the ENBT works, EN2T works intermittently.

My customer does not allow continuous tasks, which is fine with me because I never used it anyway, I don't like unpredictable scan rates that can change over time with code additions. So that's not the issue in my three instances. In this last system we do have a periodic task running at 10ms doing serial communications that's using 45% of the CPU, but the remaining logic only uses 15%. The first two systems did not have a task faster than 50ms but each did have 12 axes of K6500s. So something else is going on, possibly a combination of the EN2T, ENBT, L72 and v20 and some other condition(s).

My customer does not allow continuous tasks... So that's not the issue

Click to expand...

Did you actually remove the Continuous Task, or did you just leave it with no Program in it ?

Does your system use AC modules with Diagnostics ?

How many MESSAGE objects are active on the processor?

I've experienced a similar issue when we unknowingly exceeded the UCB limit of 10.