clueless PLC user

S7-200 programming/replacement

18 posts in this topic

Hello,

As my username implies, I am way out of my comfort zone here, but here goes.

Have a Kuhlman steam sterilzer, just shy of 20 years old, that uses the aforementioned CPU(?), to further expand on the numbers, 216-2AF22-OXBO.

Daisy chained below this are four 222-1BF22-OXAQ modules.

The problem I have is it no longer properly reads atomospheric pressure, which when idle should be around 14.7. Instead it jumps all over the place, causing an issue whenever a cycle is started.

I did find a known good replacement for the 222-1BF22-OXAQ to eliminate that possibility, but after the vendor installed it, still no change. Vendor also checked things with a signal generator, all good there....pressure transducer that generates signal good, but replaced this to be sure, still no change.

This leaves just the main CPU, and according to him this is no longer serviceable.

That said, I see these used all over and am curious if ours can either be repaired, or if I can send ours in so a replacement can be sent back programmed just the way ours is currently.

Please dumb it down for me with any questions, etc. I'm in my comfort zone under the hood of a diesel engine, not in the cabinet of this machine. I know just enough to be dangerous.

Appreciate any directions folks, thank you

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We all started out clueless with PLCs at some point, so: welcome!

I would suggest reaching out to a local integrator with S7-200 experience. Maybe ask your local Siemens distributor for a referral. I would want the integrator to first connect to the PLC and do some diagnostics, including generating a backup of the existing program. I've worked with a bunch of S7-300 and S7-400 processors and a little with the newer 1500s, but never a 200 so I don't know what to tell you to check specifically.

Once you have a backup of the program, the integrator should be able to download it to a replacement and, if that's the problem, you'll be back in business. Even if that works, I would seriously consider replacing the controls with a modern system.

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Posted (edited)

This PLC was declared obsolete in 2017

Product Lifecycle (PLM) PM410:Product cancellation
PLM Effective Date Product is cancelled since: 01.10.2017

 

You may still be able to obtain one from the likes  of Radwell.

However you would need someone with the S7 Microwin software and PPI interface cable to be able to program any replacement.

If the CPU is password protected then an upload would not be possible.

Have you connected a signal generator directly to the analog input to eliminate any wiring problems?

 

 

Edited by Moggie

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Posted (edited)

Appreciate the replies folks.

Yes, I was told it's an old setup and no longer supported, so no suprise there, and do remember the vendor telling me he would need to find someone with access to some older software.

That was as far as he coould help me out, and did suggest upgrading the entire system but then didn't express much interest due to being busy with larger projects.

Of course, the owners want to go the low cost route if possible, but I do see this as an issue even if we are able to address it as a crutch for now.

I do recall him using the signal generator directly on the analog side, yes.

Edited by clueless PLC user

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Can I ask what state or where you are located?

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23 hours ago, clueless PLC user said:

Appreciate the replies folks.

Yes, I was told it's an old setup and no longer supported, so no suprise there, and do remember the vendor telling me he would need to find someone with access to some older software.

That was as far as he coould help me out, and did suggest upgrading the entire system but then didn't express much interest due to being busy with larger projects.

Of course, the owners want to go the low cost route if possible, but I do see this as an issue even if we are able to address it as a crutch for now.

I do recall him using the signal generator directly on the analog side, yes.

So he did not actually go online to check the values being seen at the analog input by the CPU?

(and everything else works ok?)

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On 5/4/2022 at 5:01 AM, jrw said:

Can I ask what state or where you are located?

I"m in the NW corner of IA

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21 hours ago, Moggie said:

So he did not actually go online to check the values being seen at the analog input by the CPU?

(and everything else works ok?)

Pretty sure all he did was a hook signal generator up to the EM 222, of which this machine has 5, and checked it there?

This was about a year ago so I can't recall all the details. We event tried a new EM 222 which made no difference.

I know this sounds rudimentary here but I'm just giving the nuts and bolts version of what I know, nuts and bolts.

 

 

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Posted (edited)

On 03/05/2022 at 2:38 PM, clueless PLC user said:

I did find a known good replacement for the 222-1BF22-OXAQ

Is this the correct part number? I cannot find it on the Siemens web site or in the S7 200 manual.

The nearest I can find is 6ES7 222-1BF22-0XA0

The EM 222 is a digital output module.

How is the atmospheric pressure connected and displayed??

Edited by Moggie

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4 hours ago, Moggie said:

Is this the correct part number? I cannot find it on the Siemens web site or in the S7 200 manual.

The nearest I can find is 6ES7 222-1BF22-0XA0

The EM 222 is a digital output module.

How is the atmospheric pressure connected and displayed??

The pressure transducer is hooked up to a 24V terminal strip, then loops around to the module.

Readings are displayed on a Sematic touch screen control panel.

Here is where things get interesting, to me at least, and not sure why I didn't catch this earlier......like I said it's been a year since I looked at this sterilzer as we didn't really need it in operation.

The module that the transducer hooks into is a EM 231 

231-OHC22-OXAO

I have no idea why the vendor thought it would work to try a different EM 222, that as far as I can tell has nothing to do with this transducer.

Is it possible the EM 231 is bad? I did try the other three empty spots on that module but no change, guessing that has something to do with the way the CPU is programmed.

I would post a pic but for some reason I can't, even if it's the correct upload size. 

In reference to your earlier question about the part #, that was the correct one, at least it's what is listed on the front of the housing.

 

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That makes more sense. Yes, the analog input module could be bad. I'm a little concerned that a vendor tried replacing an analog module with a digital one.

Generally, you have to tell the PLC what module is in which slot, so just moving it to another slot won't work without updating the program inside the PLC.

Without having access to the programming software, the next step is probably to replace the analog input module.

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1 hour ago, clueless PLC user said:

The pressure transducer is hooked up to a 24V terminal strip, then loops around to the module.

Readings are displayed on a Sematic touch screen control panel.

Here is where things get interesting, to me at least, and not sure why I didn't catch this earlier......like I said it's been a year since I looked at this sterilzer as we didn't really need it in operation.

The module that the transducer hooks into is a EM 231 

231-OHC22-OXAO

I have no idea why the vendor thought it would work to try a different EM 222, that as far as I can tell has nothing to do with this transducer.

Is it possible the EM 231 is bad? I did try the other three empty spots on that module but no change, guessing that has something to do with the way the CPU is programmed.

I would post a pic but for some reason I can't, even if it's the correct upload size. 

In reference to your earlier question about the part #, that was the correct one, at least it's what is listed on the front of the housing.

 

Ah ok - as per Joe E this makes sense now.

Yes I would change the EM 231 module first and see what happens.

as already stated you cannot just move the wiring to a spare analog input without changing the program,

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Posted (edited)

Good info, thanks again folks.

So what you are saying is, I could try a known good  EM 321 and the PLC will still allow that 1st slot for my two wires.

There are other modules below this one, however they are only used for RTD's and are stated as such in the model # AI2-RTD

The one I am referring to says it's a 12 bit, AI4x12bit

Was able to attach a pic this time. Slot 3 is the one that reads the transducer.....slot one is the one the vendor replaced, of course the reason it's missng the slot 1 sticker. Probably nothing wrong with the original I kept

 

 

20220505_110336 (2).jpg

Edited by clueless PLC user

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Posted (edited)

12 hours ago, clueless PLC user said:

So what you are saying is, I could try a known good  EM 321 and the PLC will still allow that 1st slot for my two wires.

Correct.

 

FYI - here is a link to the S7 200 manual with details of all the cards etc.

S7-200 Programmable Controller (siemens.com)

Page 416 for details of the EM231 showing DIP switches that may need adjusting on any replacement module.

As Joe E said - it is worrying why anyone would be looking at a digital output module if the problem is with an analog input module?

Edited by Moggie

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My first thought would be that, if they used a signal generator to "simulate" a known good signal from the transducer to the analog input and it didn't read correctly, that the problem is almost certainly the analog input module. But...if they swapped the output module instead of the analog input module, I don't have a lot of confidence they did the test correctly.

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11 hours ago, Moggie said:

Correct.

 

FYI - here is a link to the S7 200 manual with details of all the cards etc.

S7-200 Programmable Controller (siemens.com)

Page 416 for details of the EM231 showing DIP switches that may need adjusting on any replacement module.

As Joe E said - it is worrying why anyone would be looking at a digital output module if the problem is with an analog input module?

 

7 hours ago, Joe E. said:

My first thought would be that, if they used a signal generator to "simulate" a known good signal from the transducer to the analog input and it didn't read correctly, that the problem is almost certainly the analog input module. But...if they swapped the output module instead of the analog input module, I don't have a lot of confidence they did the test correctly.

Appreciate the link to the info

As mentioend, I too wonder if the wrong module was tested, but at any rate why the 1st slot was replaced when it's not the issue.

I am tempted to roll the dice, purchase a good known 231 and see what happens. 

I did check the dip switches just to be sure they were set up according to the schematic, and they are still set as they were from the factory.

Thanks again folks for the ideas/info

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Posted (edited)

Well folks, purchased a refurbed EM 231 and the old girl is up and running again after a year long furlough! I was almost giddy when I saw the PSIA read 14.7 again instead of 10.4, 10.7,12.3........

Much appreciate the info and knowledge I stumbled across here from you guys, it's proven to be invaluable.

Plan now is I am going to order some spare modules, along with a CPU(providing I can still get it programmed but I am making headway there). At the least it buys us some time before we end up sinking a large sum into this machine with all updated electronics.

Am curious if anyone is familiar with the Siemens touch panels? Likely just a matter of time before it gives out, and I've located some online.

Does the panel also have to be programmed so the layout is the same as the current one?

It's of the 6AV6 545 family, and also appears no longer supported. 

Edited by clueless PLC user

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A quick Google search says it's part of the older TP family. I don't think I ever used a TP but did use the older MP series. I know the MP series used WinCC Flexible and I'm pretty sure the TP did as well. I agree that you're probably on borrowed time with the HMI; my experience with the longevity of the MPs was not good.

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