Micrologix 1000

ngilbert

Member
Join Date
Oct 2017
Location
Ohio
Posts
28
I have a micrologix 1000 that I have had to clear a fault on 3 days in a row. The error is "Unexpected Restart". We have 2 machines with this type of Micrologix and I thought about swapping the PLCs and programs to see if the problem moves to the other machine or if the other micrologix faults as well unless someone has any other suggestions. The operators claim the machine will run for a littler over an hour before the fault returns.
 
Has the PLC been working properly until recently? Is it possible that you are having power issues?

If power checks out you can do your swap or just replace the PLC. That is how I would go about finding the issues.
 
Power surges from power supply.

Grounding, check and double check it.

Surge protection on inductive loads?
 
With the ML1000, I have seen unexplained errors as a result of power quality problems, poor grounding and spikes on the output relays. In one case, we corrected it by using a line filter on the AC powered PLC. In another case, it was a matter of replacing the PLC which apparently had some internal problem.
 
Has the PLC been working properly until recently? Is it possible that you are having power issues?

If power checks out you can do your swap or just replace the PLC. That is how I would go about finding the issues.

To my knowledge this machine has not had this issue before and has been running good. I will probably just swap them tomorrow if it happens again tonight.
 
If the PLC is DC powered check the DC power supply. I have had a run of bad power supplies causing all kinds of weird things lately.
 
I went to look if we had an old 1000 to use in our storage for old PLC and there was a 1000 in there with a tag, same machine, same issue from 2012 that the old programmer worked on and he ended up replacing it. Makes me curious about why this is happening again 6 years later.
 
Do the outputs have suppressors on them? I have seen and experienced plc's faulting out for outputs not having surge suppression on them especially if the cycles are quick changing.
I would also check the wiring for loose connections but it could also be the PSU of the micrologix 1000 that is failing.

Also A/b discontinued the the ML1000 if you didn't know that, not sure if they can be still bought through your supply house I know our sales rep told me I should start looking at conversion products for them.
 
I had this same problem and I remember reading about some of 1000s being faulty.
I can’t remember where I saw it, maybe Techconnect.
Ended up replacing it with a 1100.
 
I have seen this problem on a machine that had intermittent sensor problems. Sometimes when a sensor would be triggered, the processor would fault; I'm assuming this was due to a short within the sensor or the wiring. You may want to check for any possible sources of shorts on any of the inputs. In my case, there were only four sensors; so we just replaced the sensors and all the wiring back to the inputs and the problem went away.
 
Ghost in the machine...

ngilbert said:
I have a micrologix 1000 that I have had to clear a fault on 3 days in a row. The error is "Unexpected Restart"...

Most likely the specific error is...

40877 - MicroLogix 1000 Major Error S:6 = 2h Unexpected reset occurred
Access Level: TechConnect

Linked from within that technote, you are advised to review the following technote which contains extensive information related to all the excellent advice given above, and more...

16301 - MicroLogix Controllers: Fault codes 0001H, 0002H,0004H, 0007H, 0008H, 0009H
Access Level: TechConnect

I would agree that swapping out the MicroLogix 1000 controller, if you can, would be the best place to start troubleshooting. This would first rule in or out any internal component failure that may be present. The fact that the controller will run for a similar period of time before each failure might suggest component breakdown due to temperature increase during normal operation.

Should swapping out the controller not resolve the issue, then the time delayed error might suggest another aspect of the machine operation that is interfering with the controller on either a cyclic basis, around the same time span as the failure occurrences, or an aspect of the machine's operation that is overheating or breaking down after continuous use up to the time of failure and then interfering with the controller.

A tricky one, but the historical evidence you've uncovered, that is the previous controller and it's intriguingly labelled "toe tag", would suggest that this issue was never truly resolved. A real Ghost in the machine, perhaps?

Regards,
George
 

Similar Topics

Hi all, We have a very old pit pump system running on Micrologix 1000. Now, whenever there is an alarm for high conductivity, we want that alarm...
Replies
5
Views
1,222
Looking at a Micrologix 1000 1761-L32AWA, I tried to connect using the 1761-CBL-PM02 through a Serial to USB converter (This setup was used...
Replies
2
Views
953
Hello All I am trying to convert a ML1000 program for use in a ML1400. I didn't create the original program & documentation is non existent...
Replies
14
Views
4,361
Hey Folks, I have a customer with an older machine that is controlled with a MicroLogix 1000. The machine just quit working. The power light is...
Replies
22
Views
10,409
Ive got a Micrologix 1000 that im am trying to use as a bench tester but its current setup has a password protect on it and no one here knows that...
Replies
6
Views
2,231
Back
Top Bottom