I/O led green blinking in CompactLoix 1769-L32E

Hi fellows,

Back in the forum with just another question.

I'm using a 1769-LE32 CompactLogix CPU and I got the next trouble: When a power-fault happens and rightaway the power is backed up, the PLC restarts itself but the I/O led is all the time green blinking ( like if one or several of the I/O modules are not being detected). No Major Fault is declared (no red led steady or blinking) but even though, the PLC is not up and rolling when is green blinking. If a Major Fault would be declared I could at least attempt writing a routine and place it in the Power Up-Handler folder so that when backing up the PLC, the Major Fault was automatically reset (see this topic: http://www.plctalk.net/qanda/showthread.php?t=42705&highlight=Power-Up+Handler+Program ). But this is not such case...the green blinking goes on, goes on, goes on...

The only key to this problem I've got so far, is to let about one minute going past before backing up the PLC and this is not an acceptable solution at all (think about the plant out of control after a power fault and the need of a operator being physically there for performing this operation,...out of sense).

What is worst is that we haven't yet found a solution from our local Rockwell costumer service.

Has anyone here had a similar trouble?

Hi there
Manual says:
Flashing green-->One or more devices in the controller’s I/O configuration are not responding.
Just a suggestion, how about removing the I/O cards one by one and see which one is giving the problem?

Good luck

Ruben:
Something like that happened to me the other day, I found that one board was not fitting properly, The board was OK, installed that board in another project and put a new one where the problem was located. Probably I you swap boards in your project this will solve your problems, do not know if you have to change I/O config.

Thanks for the tip Manmeet,

I had already thought of doing that but, after this problem happened for three times and more, and after having checked via the RSLinx what module/s was/were causing the fault, I could notice that each time this problem happened, the RSLinx detected a different "defective" module in the whole suite of them...so this diagnosis didn't seem to be quite reliable. It is like this unsuccessful detection of the modules happens randomly ... So my guess goes more into the CPU rather than for any module's fault.

Actually, we have another plant running a similar PLC control configuration and the same problem happens...I've even tried to swap the CPU's for both plants but it hasn't helped.

We bought both CPU's and all the rest of the I/O modules in a same stock

I've also tried to upgrade the firmware as this was what the local Rockwell customer service told us to do, but still we go on with the same poblem...

No idea what's the reason for this fault.

green blinking

widelto said:

Ruben:
Something like that happened to me the other day, I found that one board was not fitting properly, The board was OK, installed that board in another project and put a new one where the problem was located. Probably I you swap boards in your project this will solve your problems, do not know if you have to change I/O config.

Click to expand...

Thanks William, that's an interesting approach, but I'm not sure about what you mean by "board" as the CompactLogix has no chassis (it's a modular suite closed by two ending faceplates)

Are the I/O modules that don't make a connection to the CompactLogix the 1769-series modules connected directly over the Compact bus, or are they modules connected over the EtherNet/IP network ?

I have seen a few systems where very short power interruptions cause the I/O modules to not power up before the CPU itself, especially with analog I/O modules.

The next time this happens, use RSLogix 5000 to go to the Connection tab for the affected I/O modules and find out the exact error code for the connection status.

The ideal thing would be to use a UPS or buffered power supply so that both the I/O power and the main power for the controller are applied and removed at the same time.

Thanks for your approach Ken,

Answering to your question: my modules are directly connected over the Compact Bus, a very simple configuration for 4 DI modules + 1 DO module + 2 AI modules and 1 AO module, placed in the bus as following that order.

I remenber once I spent a couple of hours causing that fault to the system, simulating the fault for taking down the error codes but as far as I remenber now, I got several and different error codes. It seemed all a bit random. But I'll repeat again the experience and see what happens.

I'm gonna try to focus this trouble from the code itself...I have to study more thoroughly whether it's possible to write a routine with the GSV and SSV instruction for reseting that faults. Though I'm not 100% sure that's possible...and I rather expect the opposite.

buhnen said:

Thanks William, that's an interesting approach, but I'm not sure about what you mean by "board" as the CompactLogix has no chassis (it's a modular suite closed by two ending faceplates)

Click to expand...

Ruben:
When I said board I meant a card ( a 1769-IA16 for instance), Have you check your power supply wattage, and distance from cards to power supply. If they are too far that´s a problem.
Check ground connection just for the sake.
I always use an UPS in all my projects, try that too.

Problem solved !! ..or nearly

Thanks to the Rockwell tech support, I got some indications and explanations on how to write a routine for auto-reseting the minorfaults and majorfaults caused to the PLC right after its restart.

Perhaps this is not strictly a solution for a problem which still really happens because of a power up desynchronization both for the CPU and the modules whenever a fault and back up occurs as I can deduce from Ken's answer?

The ideal thing would be to use a UPS or buffered power supply so that both the I/O power and the main power for the controller are applied and removed at the same time.

Click to expand...

..but the thing is now I can keep my system up. I still want to check all this more thoroughly though, but in the meanwhile I'll post the code just in case it can be of assistance to any of you.

This will probably appear as a stupid question but I will ask anyway.
I would like to know if you have an end card terminator in place code ECR or ECL.
and how many cards are to the left and or the right of the power supply.

There are never stupid questions fellow. As an image is better than thousand words: See the attached picture with my stuff.

At the right end card terminator I reach to see something written like 1769- ECR....btw, what does mean that ECR code?

ECR = End Cap Right, ECL = End Cap Left

Gil47 said:

how many cards are to the left and or the right of the power supply.

Click to expand...

Gil, please download manual 1769-sg002_en-p.pdf from rockwell, attached you will find a page of this manual, take a look at Power supply distance rating, this is the maximum distance from left or right that a card can be located from the power suplly.

Also you have to add 5V and 24V currents of all cards and this shoul be less that power supply wattage.

Compactlogix L32-E I/O Issue

Gil47 said:

This will probably appear as a stupid question but I will ask anyway.
I would like to know if you have an end card terminator in place code ECR or ECL.
and how many cards are to the left and or the right of the power supply.

Click to expand...

I have a new project not seeing any of its I/O. there all configured correctly with FW.REV. and also set to compatible. Im not postive, But I dont remeber seeing a ECR installed on the end of the Buss.

Does anyone know the error if there is no ECR Installed.
Im thinking like certain types of networks if it needs a end of line terminating resistor its not Going to work properly without one.

It is a Compactlogix L32-E
This IS ERROR
Thanks In Advance.

The end cap was the Problem.