What are the causes of the PLC’s program lose?

bundhit

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Sep 2003
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Today, I found FlexLogix 5434, which has a new battery backup, faulted. Green LED at Local and Red LED at LOCAL2 were flashing. I used RSlogix5000 to online to find the fault's description. RSlogix5000 showed me the message: “ No program file in CPU”
I solved the problem by re-downloading the program to the CPU and it worked finally.
I would like to protect the PLC’s program lose in the future but I need to know the root causes firstly. Please anybody lists the possible causes that make PLC lose the program.
 
The most common cause for program loss in ANY manufacturers PLC is an incoming voltage problem of one sort or another. Most often it is Spiking due to lack of surge suppression. Next most common is grounding issues. Then frequent brownouts round out the list.

95% of the time when I have dealt with this problem it has been spiking. Always use as good surge suppression as you can afford. If for lack of anything else use a couple of MOV's.

Personally I recommend a good quality TVSS unit (Transient Voltage Surge Suppressor.)
 
I've seen this many times with the Koyo PLCs. Make sure you've got a good ground and a good surge protector. We use a Panamax MAX-2 on all of our 120VAC control panels. Its expensive, but well worth it in the long run.
 
Program Loss

Another possibility (it has happened to me) is that when the power supply is too old, it does not hold up well for the battery backup.
Replace the PS by a new one, and it will result in less trouble.
 
I won't say it can't be the Power Supply, but I really doubt it. Even old power supplies don't usually cause a memory erase. An old battery can because power was lost, but I have ran across extremely few cases that I could point to a PLC power supply and say, "Therein lies the culprit."

[begin Rant]

On the other hand, I can't even begin to count the number of times that I have looked at a system and shook my head at the lack of surge protection. Not to mention the number of times I have worked on a system where the incoming power had surge protection, but all of the relays, contactors, solenoids, and other noise producing circuitry that was downstream from said protection with nothing on it to prevent CEMF and surging from damaging a PLC or expensive HMI.

[/end Rant]
 
As far as know this is a known feature of most AB processors, including PLC5 and all Logix processors.

If firmware detected that program in the memory is no longer valid, corrupted or not safe to continue, processor will erase program.

If some cases processor will create dump file called IBDead.
A-B has utility to extract this info and send it for research.

Hope someone from A-B will confirm this here.
 
My most frequent cause for program loss is voltage spikes. This is even in systems with powerline filters and mov's.

My second most common cuase is power loss or brownouts, even with a working battery in the memory.

Third most common cause is power supplies.

Fourth is cpu module, once for sure, possibly twice, in 16 years.

There have been some unidentified, generally attributed to the keebler elves.

My guess, is that even with a protected machine, a spike or surge hits the memory module with all I's or all 0's, and attempts to be the new memory, and the cpu doesn't know any better.

Better think this one out over a cold one....
"1 1 0 0 0 1 1 bottles of beer on the wall", oh wait, that's part of another thread.

regards.....casey
 
PLC flex logix 5434 problem

I am also having the same problem with my plc .The I/O led is off and the plc is not working .As u said do u think i too hsve to reload the program
 
I think due to low battery i.e 1756-BA1 battery.I should be changed if Battery LED flashes RED.I happened with my plc.
 
Friends ,

In my case the I/o led is off in the plc .the led at local is flashing green and led at local 2 is flashing red.It happened after changing the old discharged battery with new one.What could be the reason.
plz suggest me.
 
I used RSlogix5000 to online to find the fault's description. RSlogix5000 showed me the message: “ No program file in CPU”
If this PLC is connected to a comm network with outside connections to the Internet, also look for viruses, worms, and other malicious programs. Several different countrie's government intelligence agencies are fighting a cyber war against the Iranian nuclear program and the Iranians are fighting back. The first round used the finely-targeted Stuxnet worms, but the Iranians fought back using messier methods and attacked banks, power plants, and many other facilities. As with any war, there will be widespread civilian casulaites in many countries, that will never know what hit them.
 
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I have the same problem with a Schneider TSX plc;and in my case this is due to battery failure
If the machine Stay off during more than 4 days, the progamm is lost and I'm obliged to download the programm
I'm not famiiliar with AB plcs, but usually with Siemens plcs you can add a memory module.
 
@Lancie1

AFAIK, Stuxnet only attacked Siemens PLC's. We got hammered hard on our Logix 5k's when Code Red appeared, but that was due to the high volume of traffic on the network that clogged communications (scheduling).

Siemens isn't the only manufacturer to have vulns, but it's the only one that I know of that has been exploited.
 

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