Modicon Micro 984 Lost Run

Join Date
May 2002
Posts
9
One of our 984 machines lost it's run command last night. I have seen these machines loose the program before but never just the run command. The power supply appears to be a happy camper but I still have a Fluke on it to check for any drops, nothing so far though. I also found out that the same thing happened on this PLC earlier in the week. It will not return to run after a reboot, the only way to crank it back up is to hook up the laptop and start that way.

Has anybody ever had a similar experience? Any ideas on what we might check. Modicon trouble shooting guide does not have much information, wait I am sorry we don't have a trouble shooting guide. HELP!
 
take this with a grain of salt (whatever that phrase means)

Just a thought..... Does the 984 have an EEPROM? I know that when you flash the EEPROM on the Modicon Micro, it asks you if you want the PLC to automatically start when program is automatically restored by the flash memory. You did say that you have lost programs, I haven't had this happen to me, but I can think of a scenario where if you lost the program and the flash would restore the original program but wouldn't start the plc. In that scenario, it would appear as if all that happened was the plc stopping. ---clear as mud?
 
I have to say I am sorry, I was having personal processor problems last night while I was typing. The Derek Frerichs 1961 is a 40 year old CPU that has problems processing when the Wife main frame is trying to put data into one of it's two I/O ports. What I meant to say was a Modicon Compact 984 not a Micro. I have a Micro on my desk that we play with but it was not the brick that was the problem it was the Compact.

I'm not sure about the EEPROM to tell you the truth. I'll have to check into that. I could see where that could cause it to forget to go to run. I'll play with that this weekend when we are shut down for maintenance.

As for the loosing program that comes from a dead battery and a plant manager who does not think we need the Flash backup. They are sooooo expensive. Oh the wisdom of the folks in the carpeted offices.
 
I do believe that you had a power blip and the processor is not
set up to re-start. I cant remember at this time where to configure this. But I'm sure you can figure it out. If this is what you want to do.
 
Hi,
I have 22 different Machines having these Modicon 984 PLC and usually I face this same problem once in a month, few days ago I attached a event recoder parallel to the PLC powersupply and found that if there is a fluctuation in the supply, PLC looses the program(PLC batteries are OK ).To get rid of the problem I am planning to attach a online UPS before PLCs.
 
Excellent idea! I actually feel pretty stupid right now because this something I preach to everyone about their PC's. We will certainly set a few of these up on our machines. Thanks for slapping me awake!
Have a great one! bonkhead
 
984 Stuff

I have about 65 MIcro 984's and One standerd 984
Its a Wal-Mart Distribution Center, lots of PLC's here.
Any way Use the PCI EProms cards thats the way to go,
Just restart cabinet its all good. very few problems
MEzz Out
 

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