ControlLogix 1757-SRM failure

ashley · Apr 26, 2005

We have a problem with a 1757-SRM module used in one of our projects. The OK LED on the SRM is solid red and the power up self test gets stuck on TH02.

In fact this is the second instance, in the past eight months, of an SRM module failing. We had a similar case where in the SRM stops on self test TH73 and the OK LED is solid red.

Response from Rockwell Support was to replace the SRM module. This is one expensive module to keep replacing everytime it fails.

Firmware revision of both the 1757-SRMs: 3.25

Any similar experiences? Any thoughts/suggestions?

Appreciate your help.

jstolaruk · Apr 26, 2005

Are you also using the Redundant Power Supply 1756-PX75R?

ashley · Apr 26, 2005

No, just the 1756-PA72.

akreel · Apr 26, 2005

jstolaruk said:
Are you also using the Redundant Power Supply 1756-PX75R?

Wouldn't that require four of them? EEEEEW!

akreel · Apr 26, 2005

ashley said:
In fact this is the second instance, in the past eight months, of an SRM module failing. We had a similar case where in the SRM stops on self test TH73 and the OK LED is solid red.

Can you say something about the installation?

What's nearby: VFD's, lighting, high magnetic fields?
What kind of enclosure is the PLC in: NEMA4X, NEMA12, a workbench?
What's the environment like: clean, dusty, corrosive, noisy (vibration)?
Where's your power coming from?

In other words, can you think of any reason the modules might be failing? If not, you SHOULD be getting them replaced under warranty.

AK

jstolaruk · Apr 26, 2005

You'd think A-B would get involved considering it could be a "failure" of a product that "shouldn't" fail; at least to check out the circumstances.

jstolaruk · Apr 26, 2005

Another dumb question, are you using one of the 1756-SRCx cables to connect the SRM modules together?

ashley · Apr 27, 2005

Thanks guys.

akreel,
The 2 SRMs failed in 2 different locations.
There are no VFDs or high magnetic fields nearby in both locations.
In one case the PLC is in a panel with glass door, the door is kept closed all the time (environment absolutely clean). While in the second case it is a panel with metal doors (environment slightly dusty).
Power seems to be OK too coz we don't have a problem with any of the other modules - processors, communication modules, IO modules, etc. The first module failed just after a year of purchase from Rockwell and the second one around 8 months after that, so they will not replace it under warranty.

jstolaruk,
All we got from Rockwell was to replace the modules. Yes, we are using the 1757-SRC1 cable to connect the SRMs together.

jstolaruk · Apr 27, 2005

I know this may not be of any help but the last time I/we installed a PLC with a hot backup, the customer paid to have the design and installation certified by a PE and Allen Bradly; not unlike the procedure we use when designing, building, and installing a CE certified panel. I'm not even sure that A-B offers this service anymore.

akreel · Apr 27, 2005

After two failures things start to look suspicious. If there were three, I'd suspect a conspiracy (or a gross error in the installation).

You returned the modules for evaluation, right? Did you get ANY feedback as to why these modules failed? At the very least, you're owed an explanation as to what the failure displayed on the module means. You bought two new modules plus the four orginals if my count is correct. You've certainly paid enough to warrant some support.

Has anyone told you (in detail) what the failure displayed means? Did you check the knowledgebase on AB's website?

AK

ashley · Apr 28, 2005

The first failed module is still lying with me in my office. The cost of repair is almost the cost of a new SRM module. The second one is still on site. I can get it only after I replace it with a new one.

Here is the response from Tech Support for the first failure:

"Case Number: 3682110 Msg: Ashley,Re: 1757-SRM error TH73 means ?All of the 'THxx' codes are powerup self tests that the SRM does before declaring itself good. If they're getting one of these, then it's likely that they have improperly functioning hardware, and may need a module swap. Try replacing the 1757-SRM.Hope this helpsregards,Rockwell Automation Tech Support"

The knowledgebase doesn't have any information on these codes.

Thanks for your interest and concern, appreciate it.

akreel · Apr 28, 2005

ashley said:
If they're getting one of these, then it's likely that they have improperly functioning hardware, and may need a module swap.

When you get answers like this, be sure to call your distributor. They'll help you bump this up the chain of command, and get you better results. No sense paying for extra modules if these (maybe)had flaws.

ashley · May 1, 2005

Irony

We are the distributors for Rockwell Automation in Kuwait. Looks like I will have to pursue this further with Rockwell.
Also, just wanted to keep the topic on top, in case anyone missed it earlier.

Regards.

Contr_Conn · May 1, 2005

ashley:
Did you try faulty SRMs in the diffrent empty rack?
It is possible that something else kills it in working system.

Techsupport is correct - if module display THxx - it means something is wrong with it and module should be replaced.
THxx identifies internal functionality test and if it failed, nothing can be done on the field.

To identify what actually happened with modules, you should send them for failure analysis (it is not free) and get Rockwell Field service engineer on site to examine whole system. It should be an external reason for sysytem to fail.

Also I would recommend to flash whole system to the latest FW from Redundancy Bundle ver 11 or 13. Don't flash one module, flash ALL modules. Flashing one module is useless.

TonyBabu · May 2, 2005

We have the secondary SRM error with display message DISQ on secondary SRM module. We try to check from RSLinx but we not found Primary SRM configuration. In the RSLinx, we found:
Primary:
Logix 5555, 1756-CNB, 1756-CNBT
Secondary:
Logix 5555, 1756-CNB, 1756-CNBT, 1757-SRM
How to solve this problem?
Thank you.
Tony

ControlLogix 1757-SRM failure

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