MicroLogix 1500 loss of program

Has anyone got any info on why a micrologix1500 PLC would just "lose its program"?
The PLC was only installed a month ago, the battery is new and has no "low battery" lamp illuminated, yet, I was called to check why the system wouldn't run and there was just the end instruction in the PLC and that was all.
I reloaded the program and off it went. The client is quite rightly concerned that this may happen again. I have never had this happen before, any suggestions?
By the way, there was no loss of power or anything unusual that may have caused this and the fault light was illuminated prior to the sparky cycling the run/prgram switch, after which the run light was lit, but of course, with no prgram.

Steve

What I know about micrologix 1500 plc you could write on the back of a postage stamp in block capitals.

But, it seems a bit suspicious that one of your clients spark's had a fiddle with the PLC. Is it possible that he proformed a master reset thus wiping your program?

That way if your client is concerned about this happening again perhaps a memo to his staff not to fiddle would cure this problem.

Paul

I'm with Paul on this one, sounds a bit fishy. Does anybody in the company have the ability to edit the ladder logic in the machine?

I'm just copying what he said....

Originally Posted by Ken Roach in the RSLogix Forum.....

In virtually every installation I've seen with this problem, a big fat green chassis ground wire has been the solution. I usually make the chassis ground wire for MicroLogix about two gauge sizes larger than the power supply wires. #8 AWG isn't overkill if you're having memory failures.

The MicroLogix memories can get scrambled by ground plane noise, or especially by unsuppressed inductive output loads. When the memory fails it's checksum, the Micro declares a major fault and clears the program. Much better than continuing on with corrupted memory, I think you'll agree.

There was a susceptiblility in some AC-powered, AC-Input MicroLogix controllers about three years ago, I think with Series C. In high noise environments, they met the specifications but with less fudging room than the earlier (or later) ones.

There are a couple of A-B knowledgebase documents about this topic too... review document G16443 on support.rockwellautomation.com.

Click to expand...

I wouldnt blame the loss (especially a first time loss) to the brand/model plc, losing a program is nothing unusual. Losing a program OFTEN is a problem, any plc can have glitches.

As stated before, sparky's can do things. ALSO there are power glitches/surges etc that aren't seen. There are issues that can create a woodpecker effect that cause problems with any electronic device.

This will be one of those wait and see what happens kind of things. Whatever you do, do NOT assume that its all the plc's fault at the beginning, that can/will be detrimental to troubleshooting the problem.

In a similiar vein

On our vaunted (and expensive) Steeplechase-powered production line, I got a call-in two weeks ago that the system was refusing to boot. Did a little digging and lo-and-behold, the entire VLC software suite had been uninstalled. Our project programs and a handful of drivers were all that remained.

We re-installed the software to the computer, and off she ran like a champ. Our second-shift man the night of the incidenct reported his 18-year-old temp-agency "helper" had been screwing around with the computer just before the machine died. When confronted, the kid admitted he had uninstalled the software, and was fired on the spot.

It's not just the sparkies you gotta watch for. I used to say "nothing scares me like a superivisor with a screwdriver". These days, it's "an operator with a mouse".

TM

Yeah, Steeplechase plays hell with the video performance on Quake III.

If you can, go online with the "DEFAULT" program and examine the fault code. Often that will give you a hint about why the controller has defaulted the application program. Hex code 0x08 was the classic fault code in Micro 1000's, but it may be different in the 1500.

My comments on grounding of any plastic-cased controller still stand; BIG FAT GREEN WIRE.

Program Lost

A/B's Micro-Logic 1500 seires units is about as bullet proof as they come. I have had these things operating in the transformer room of an electric arc furnance for two plus years with no problem from noise or personnel. But, as has been stated good grounding is the key to the units life and programers minds. But again as stated, I would suggest you look at the human side of the this program going south.
By the way, what did A/B say about this.
Good Luck.

noise problems

My opinion is that you most probably are experiencing some sort of noise problem as mentioned by others.
I do not share the opinion that Micrologix or for that matter SLC's are as bullet proof as they come.
Not at all. Over the years I have been involved in many different installations where SLC's and Micrologix's (what would be the plural for Micrologix?) were used. In some installations I have experienced noise problems if and when I did not provide proper noise suppression and good grounding.

First of all you need to have proper noise filter on the PLC Power Supply. Transtector or Islatrol make such filters, do some investigation into it.
Secondly you need to suppress all inductive loads driven by PLC's
outputs. This is a must on all SLC and Micrologix installations!
Thirdly, the RS-232 port is not optoisolated and if used for HMI
or for some other reason, the noise maybe getting in this way.
You can purchase an RS-232 in line optoisolator from a Company like
B&B electronics.

Providing a good solid grounding goes without saying, it is a must.

Just because an enclosure is made out of plastic that does not mean that it does not have EMI/RFI noise suppression properties!
Modern plastic electronic enclosures have EMI/RFI suppression
built in, though I don't know if Micrologix does?

Lastly, the power supply within the Micrologix is a switching type
and as you know switching power supplies are a great source of noise.
Under normal conditions the processor is shielded from this noise but who knows what might have happened.

One more thing, based on my experience PLC5's have much higher noise immunity then either the Micrologix or the SLC500.

Sounds to me like the program isn't stored in permanent memory. When you load a program from your computer to your plc, the program goes into temporary memory. After the program is verified, you the need to load it into EEPROM. Your software manual should be able to walk you through this.

robert jes so you will know AB doesnt work that way in most cases. For that matter NO PLC will work for months being turned on/off with the program in RAM/Volatile memory. For that matter there is a need for some source of power to maintain values loaded...ie battery BUT the code/program written to the plc isnt always dependent on the battery...nowadays rarely is.

AB yes, B+R no...

I think Robert is just mistook. We have four B+R System 2005 controls, and that is precisely how they work - saved changes have to be moved into the eprom to become permanent, or everything gets deleted at power-down. This is nice for tests, but a pain in the ascot if you forget to "hard-save" before disconnecting and the lights go out.

AB, of course, does not work that way.

TM

watch the externally avalible 24 VDC out terminal if for any reason these become shorted or draw down the internal power supply the game is over.

I agree 100% with the noise suppression theory. I came to work with a company which had a number of SLC's and Microloxgix controllers. They had fault "glitches" that would shut down the processor, sometimes requiring a re-load of the program. When I cheked the programs there was no reason for the faults. I found there was no suppression on any of the relays or motor starters. When I added this, all the "Bugs" went away. Several years now..