Mitsubishi QnA stops process every month - Help please

[brucechase]

I have a problem with a Mitsubishi QnA series that happens once every 28 days at exactly 4:30 in the afternoon (at least for all of 2010). I am not that familiar with the Mitsubishi but something is telling me that I need to be looking at any rungs that have clock functions in them.

Well, I have found several rungs that are similar to below:

B10 ------------ [PLS M8]


B10 ------------ [DATERD D162]
|
------- [DATEWR W399]
|
------ [BCD W399 D30]
|
------ [BCD W39A D31]
|
(AND THIS REPEATS FOR 6 RUNGS THEN)
|
------- [MOV H800 D20]



M8 --------------- [BMOV D30 D50 K7]
|
------- [MOV H800 D40]
|
------- [BMOV D30 D70 K7]
|
------- [MOV H800 D60]


Sorry for the crude ladder logic, but that was the fastest way for me to try to post something.

Anyway, I am not sure where the real time clock is in this unit or how to reset it or even if this is the cause. One other thing for me to consider is this is hooked up to a PC that sends and receives data and there could be something from the outside writing to a bit to stop the process (the IT engineer said that he didn't do anything - but I've heard that before).

I know there isn't a lot of information here, but I can't post the program (don't know how and my company won't let me even if I did). This will happen today and I will be online looking at the process, but I am open for any suggestions.

 

[milldrone]

(the IT engineer said that he didn't do anything - but I've heard that before).

I cannot help with your problem, but the above claim got me to chuckle. I have been exposed to a variant claim made by millwrights. "We don't know what happened, it just stopped". One of the millwrights has a screwdriver in his hand with the tip burned off.

 

[parky]

If you goto diagnostics, that will tel you where the error is i.e. sep number this wil show you the exact location of the problem, it does seem to be in some sort of date/time processing or where date/time is used to perform some kind of processing

 

[brucechase]

Thanks parky, but diagnostics show nothing. It only shows that there is a loss of AC power once per month when this happens (that is how the operators recover). The processor doesn't error, just the entire process stops (almost like an e-stop but no loss of power) and the operators have to pull everything off the conveyor and reinduct them back in.

The only place where there is date and time is in the 3 rungs I kinda posted. I haven't found where it does anything else in the program. It is weird that it is every 4th Friday, and not any other Friday. The next time this should happen we will be shut down for our summer outage. I guess I will revisit in 2 months if I don't find anything before then.

 

[parky]

If they are powering down & the processor goes back into run then there will be no error, you must go online when plc is in stop mode to see the error

 

[Goody]

I know you said not - but you need to put the program up on here. Then we can see for sure exactly what it is doing.

I hardly think anyone would be stealing and using it.

But if you want a definite answer you will have to post it.