Omron C28K problems, Emergency!!

Any assistance would be much appreciated. Thank you in advance.

Here's the problem. We have a punch press which has an Omron C28K-CDR-A PLC. About 6 years ago, one of our former maint guys hooked something wrong up to the inputs and the thing went dead. We sent someone about 200 miles away, to the press mfg and picked up a new C28K unit. When he returned with the new unit, the EPROM was pulled from the dead unit and put in the new unit and all was fine until about a couple days ago.

One of the inputs, which is not wired to anything or used started indicating on. That input is for the foot switch, which we have none. Per the manual and in the programming, if the foot input is on, the press can only be run in single stroke. We need inching regularly, so this is a considerable problem.

A couple years ago, I had the old unit fixed. All it was, was that a fuse for the 24vdc power for the inputs was burned out. The unit was repaired and tested and said to be good. We also have another C28K that came out of an old conveyor we tore apart and was also known to be in good working order.

So this should be a simple problem to hash out, right? Switch the dip switches for EPROM use (00110100), swap the chip, install. No go! The repaired unit had nothing stored in it, as viewed with the programming console we have. (Keypad unit, screws on the front of the PLC.) At power up, it stated mem error. The other unit had a program in ram yet, which I later cleared. When put in the machine with the EPROM chip, from the unit that is working, I get the same results with both of those spare C28ks. I can make one single stroke in the inch mode, then it's as if the program hangs and I can do nothing more. When watching the program online, portions of the program are still running and if I trip out the guard or lube inputs, the PLC still flashes the error codes through it's outputs, as would be normal. So I put the Eprom back in the limping unit and it works as before, but no inching due to the input being stuck on.

I borrowed the LSS (DOS) software and host link unit from a local shop, transfered the program from limpy, into my old laptop. I then installed that repaired, original PLC in the press, changed dip switched for ram use (11000100), sent the program to the PLC and I get the same results as when I tried it with the EPROM chip in it. One single stroke in inch mode. If I put the PLC into program mode and clear out some data areas (HR CNT & DM, I think.) I can then make one more full stroke in inch after puttin gback into run mode. It seems that it makes no difference if I run the PLCs with the chip or from RAM. I am very reluctant to experiment with the limping PLC or our "spare" PLCs with the EPROM in them, for obvious reasons.

I tried the last 2 days to get a hold of the press mfg, but they must have a long holiday vacation. What baffles me is why those other 2 good PLCs will not work with the EPROM chip installed. The one is the original from the press. Is it possible that when we bought the new PLC 6 years back, from the mfg, that there was something else in the ram or other memory area that worked in conjunction with the stored program on the EPROM chip? Any other ideas why a simple chip swap does not do the trick?

I have to go back in tomorrow (cutting my long weekend short) and experiment some more. Cautiously, I might add. Any ideas or suggestions might get me back home with my family sooner.

Thanks again,

Dale

You may want to also post your problem at:

http://www.mrplc.com/ There is a section devoted to only Omron.

With all the PLC switching, have you determined that the foot switch input is still the trouble? (comming on with nothing wired to it)

I don't know anything about Omron PLC's, but is it possible that the foot switch input is forced on? Is there some type of operator interface that could be writting to the same memory location? When you go online with the plc, is there some other input or bit in parallel with the footswitch input that can cause the same response? Never mind that last one, you did mention that the input led was on.

I to am not familiar with the Omron PLC, but is there something communicating to it (peer to peer) and/or setting or using it in a move or copy register and changing a bit that is associated with it?,

hope you see your family, if you see mine tell them I said hello

The foot switch input on this press was never wired to anything. One day the input just came on. Would not be a force involved in the programming. When I put the chip onor dump the program into ram in the spare PLCs that input does not come on and I am able to make that one insing stroke. The PLC stands alone so nothing else attached that could have told it to do anything like that. I think the years of pounding took it's toll on the PLC. I did split the 2 halves of the bad PLC, to see if I could see where anything had run down inside it and short the input, but internally it looked rather clean. For the time being, I don't think I'm going to touch the unit with the stuck input. We can fire the line up as is. Only testing on the spares. If I knew more about programming on these Omrons, I'd just write my own stuff to run the press, but each time I look into an Omron, I find things in the programming that I don't understand.

Why don't you go online, run a findall on the input, and since you're not using it, disable those functions (put a never made XIC in front of them)?

I didn't I could do that, seeing that the program is stored on the EPROM chip. Can I?

Can you post your LSS program?

Why cant you just remove the input instruction from the program and run it from ram? Which input is showing on? Is there a mov or some other instruction writing to DM IR 00? Maybe a pointer (making it really hard to figure out)?

You have dip 7 off, are you using a drum counter? (Only dips 1-4 effect Ram/Rom selection.)

elevmike said:

Can you post your LSS program?

Why cant you just remove the input instruction from the program and run it from ram? Which input is showing on? Is there a mov or some other instruction writing to DM IR 00? Maybe a pointer (making it really hard to figure out)?

You have dip 7 off, are you using a drum counter? (Only dips 1-4 effect Ram/Rom selection.)

Click to expand...

I'll see if I can post the LSS file for that machine.

I have tried using the EPROM chip and running from ram in those spare PLCs and the actions are the same. One single stroke in inch mode, then can't do anything until the data areas are cleared out. If I can get the program to run from RAM, I might prefer such as I could tweak if needed. As long as the bad PLC is running on the EPROM, I don't beleive I can remove the references to the foot switch input.

Input 000 is used woth a prox switch to count 40 teeth on a wheel and is used for the brake monitor. Input 001 detects a tab which resets the brake mon counter and tells the press to release the clutch for top stop.

If you can see the program in LSS then you should be able to save it on your PC, then remove the Eprom, reset the dips and reload the edited program in RAM. What part of DM is being cleard that allows it to run a single stroke? It seems to me that there may be a few messed up instructions, causing some data to be placed in the input image resister, making it appear that the unused input is on. Try to save and post the program and tell us exactly what input is the culpret. Hopefully it's not too complicated....If you have any program documentation, that would be helpfull also.

The only program documentation I have was off the electrical print and I added that to the LSS ladder.

When online with the spare units running this program in RAM, from the pull down menu there is a selection to clear the data areas. I'm not near the PLCs now, so I can not tell exactly whick memory areas it allows me to clear. There is 3 areas though and I beleive it is HR, CNT & DM. In that menu, there is a space between the first area and the secon area, so it appears there is a 4th area that is blacked and not available for me and/or this modle of PLC. I tried clearing each individually, but could not get another single inching stroke unless I cleared all 3.

Now if I can find out how to attach the LSS library file!

dalem,

I have LSS2 & a c40k somewhere, but I wont be able to look at it till tomarrow or Monday. The other question is do you have the manuals? (I have hard copies but nothing to post or email).

I do have a couple manuals that I downloaded for programming the Omron PLCs, plus the one for the LSS (SYSMATE?)program. Used them a few time to modify a couple conveyors with the keypad console attached to the front of those PLCs. Think those are C200 units. (Been awhile)

Spares are hard to buy as that model is no longer made. They are for sale on E-Bay

http://cgi.ebay.com/Omron-C28K-PLC_W0QQitemZ7576167895QQcategoryZ97184QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

dalem said:

I do have a couple manuals that I downloaded for programming the Omron PLCs, plus the one for the LSS (SYSMATE?)program. Used them a few time to modify a couple conveyors with the keypad console attached to the front of those PLCs. Think those are C200 units. (Been awhile)

Click to expand...

Unless your really famillier with the C-whatever-K you'll likely need the users manual. There are actually TWO manuals. One is the installiation manual, and the other one is the programming manual. Right click and select "save-as"

http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookupByUniqueID/848E814B140664398625691F006CDDCE/$File/M11W146E150400.pdf?OpenElement

My 1st guess from what your discribing is that the Eprom has been damaged somehow changing maybe a single value or instruction. Rare event but it can and dos happen. If you can get a copy of the origional program from some old disk or printout it would be pretty easy (but time consuming) to find. Then just load the corrected program and ram and your off and running.