How do I fix this?

[iwire]

It will always be there for you or whoever is working on the system. You could lock it in a cabinet near the conveyor and put the key inside the panel.

Without a doubt you have never worked in the type of situation I have here. There is no way that would work, these places cannot even hang onto as built plans. The next guy is likely a guy from the back of the local paper advertising wallpapering, yard cleaning and electrical work.

It's retail, the turn over is high, and no one gives a darn about any item other than the cash registrar but thanks anyway.

 

[iwire]

I am heading back to it tomorrow, maybe I can get a video.

It depends if I can hide the location.

 

[Strathead]

Where am I getting this map?

:?


Are you suggesting making dozens of input combinations and noting any output changes?

With all the internal trickery that can be done in the programing I do not see that as realistic.

Sorry, I simplified it a little bit. The PLC was identified by others. Here is the manual. http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1761-um003_-en-p.pdf

This is the easy way. What I meant was, you have either on/off inputs and on/off outputs or you have variable inputs and/or outputs. From all of your description you likely on have discrete, or on/off for both in and out, that makes it easier. They can be recognized by the terminal markings on the PLC as the easy way. Analog usually has a shield that is landed at the PLC. Once you know that they are all discrete and that, for example, the photo eye in question is closed when unblocked and open when blocked, a meter does the rest.

There are other complexities as well, that i almost forgot, and that is whether the periphery devices are powered from the PLC or not. A photo eye may very well get only the power to operate it from a power supply and the contact is a dry contact that interrupts a signal (voltage) from the PLC back to the PLC. It might, however, get power to operate and power to the contact from the separate source and only require the voltage presence at the PLC. This isn't hard to figure out though. Because in the first scenario, two wires come from the PLC to the device, in the second, one wire from the PLC goes to a common for the power supply instead.

Don't get me wrong, anything you do is time consuming, when you are in learning mode. The secret is not to be intimidated. In the end it all breaks down to one wire one path and one electron. Sorry just trying to sooth. But the thing is, if you can trace out a motor start circuit or a set of three way/four way switches you can trace out this. It just takes patience and a refusal to get overwhelmed. In the long run it can be worth it because it gets easier.

 

[kwired]

Is there a manufacturer and model number or is is more of a custom build item and this is essentially one of a kind item?

Even if it was a manufactured item - over time some of those items get field customized and any info you get from OEM may not be current to what you now have.

Does look like what you have shouldn't be all that complex of a program though, you just need to gain access to that program if you want to see what it is, which means either paying for the software, or getting someone that already has it to help out.

 

[iwire]

Is there a manufacturer and model number or is is more of a custom build item and this is essentially one of a kind item?

One more time

I can not find any info at all. None. Zip.

Even if it was a manufactured item - over time some of those items get field customized and any info you get from OEM may not be current to what you now have.

The wiring seems untouched.

Does look like what you have shouldn't be all that complex of a program though,

I agree, it is running three small motors and some indicator lights based on maybe 10 total inputs.

 

[jim dungar]

...As I did explain above now with photo1 replaced when a bin breaks the beam of photo2 all motors stop and cannot be restated until the bin is removed from the beam.

Previous to my arrival and replacement of photo1 the machine was delivering bins nonstop and breaking the beam of photo2 had no effect on the machine.

Maybe you have already fixed the conveyor and it is now operating the way it was designed.
It sounds like PE-2 is there to prevent jam ups inside of the conveyor. Does the conveyor 'automatically restart' when PE-@ is cleared?

The customer may be asking you to return it to an improper continuously running state.:?

 

[iwire]

Sorry, I simplified it a little bit. The PLC was identified by others. Here is the manual. http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1761-um003_-en-p.pdf

This is the easy way. What I meant was, you have either on/off inputs and on/off outputs or you have variable inputs and/or outputs. From all of your description you likely on have discrete, or on/off for both in and out, that makes it easier. They can be recognized by the terminal markings on the PLC as the easy way. Analog usually has a shield that is landed at the PLC. Once you know that they are all discrete and that, for example, the photo eye in question is closed when unblocked and open when blocked, a meter does the rest.

There are other complexities as well, that i almost forgot, and that is whether the periphery devices are powered from the PLC or not. A photo eye may very well get only the power to operate it from a power supply and the contact is a dry contact that interrupts a signal (voltage) from the PLC back to the PLC. It might, however, get power to operate and power to the contact from the separate source and only require the voltage presence at the PLC. This isn't hard to figure out though. Because in the first scenario, two wires come from the PLC to the device, in the second, one wire from the PLC goes to a common for the power supply instead.

Don't get me wrong, anything you do is time consuming, when you are in learning mode. The secret is not to be intimidated. In the end it all breaks down to one wire one path and one electron. Sorry just trying to sooth. But the thing is, if you can trace out a motor start circuit or a set of three way/four way switches you can trace out this. It just takes patience and a refusal to get overwhelmed. In the long run it can be worth it because it gets easier.

Its all AO/AI no VO or VI.

The Phote eyes are constant powered 120 from a control transformer.


It is not that I never work with PLCs, all the supermarkets I work in use PLCs to run the refrigeration, HVAC and lighting however these units are very user friendly with touch screens allowing access to what is supposed to be happening. If an AO is in the wrong state I can quickly back track and likely see what is the reason it is in the current state. All the temp probes are VIs so you can see if its open, shorted or a legitimate value in between etc.

I am going back tomorrow to try a couple of things and if that does not work out I will recommend that they get an AB tech involved.

Thanks, Bob

 

[MattS87]

]


It has three parts, a standard horizontal conveyor on each level and vertical conveyor between them like this one. A very simple machine, a total of three motors and maybe eight safety switches.

Only for smaller bins.

Could you edit this image to show the locations of the photo eyes in question? It sounds like they would be to the infeed of the vertical conveyor. If so, is it possible that the bin stops @ P.E. #2 until a bin passes by a photo eye at the bottom so the machine knows the vertical conveyor is empty?

 

[gar]

1612226-2434 EST

iwire:

I totally missed seeing the picture of the conveyor system. As suggested by someone above if you describe or point out where photo-sensors or other inputs are located, then that can help a lot.

From the picture:

1. A pallet containing a bin is loaded on the bottom conveyor from a forklift.

2. There is a single vertical elevator that lifts a pallet and bin from one vertical position to another upper vertical position where there is another conveyor that the pallet and bin are transfered to.

3. This transfer of one pallet and bin from the lower horizontal conveyor to a position on the upper conveyor has to be completed before the elevator is allowed to returned from the upper position to the lower position.

4. The elevator must be in its lowered position before a new pallet and bin can be loaded on the elevator.

5. When the elevator is down, signalled by something, assume a limit switch, then when a pallet and bin are in the load position where the forklift positions them, then the pallet and bin can be moved to the elevator. Is Photo-1 at this load position? Does an operator have to operate a button to cause the transfoer on to the elevator?

6. What detects that the pallet and bin are in proper position on the elevator?

7. Once (6) occurs, then I assume the elevator automatically moves from the lower position to its upper position.

8. Something has to detect that the elevator arrived at the upper position.

9. After (8) occurs the pallet and bin are automatically moved from the elevator to the upper conveyor. But this only can be allowed if there is a place on the upper conveyor for the pallet and bin to go. Possibly Photo-2 somewhere here.

How close is this to the sequence?

.

 

[K8MHZ]

Its all AO/AI no VO or VI.

The Phote eyes are constant powered 120 from a control transformer.


It is not that I never work with PLCs, all the supermarkets I work in use PLCs to run the refrigeration, HVAC and lighting however these units are very user friendly with touch screens allowing access to what is supposed to be happening. If an AO is in the wrong state I can quickly back track and likely see what is the reason it is in the current state. All the temp probes are VIs so you can see if its open, shorted or a legitimate value in between etc.

I am going back tomorrow to try a couple of things and if that does not work out I will recommend that they get an AB tech involved.

Thanks, Bob

Are the HVAC / refrigeration 'PLC's you are working on 'Einsteins' or the like? If so, you will find them quite a bit different from an A/B PLC. The techs I worked with that programmed the Einsteins didn't even call them PLC's.

I don't know if that is much help to you, but I thought I would let you know that from working with both types, I found them to be completely different animals.

 

[kwired]

Are the HVAC / refrigeration 'PLC's you are working on 'Einsteins' or the like? If so, you will find them quite a bit different from an A/B PLC. The techs I worked with that programmed the Einsteins didn't even call them PLC's.

I don't know if that is much help to you, but I thought I would let you know that from working with both types, I found them to be completely different animals.

Sort of like the processor and firmware of a VFD. It has a fairly specific purpose and the program is not going to be easily changeable. It may have user parameters that can be changed but the base program is still pretty fixed.

 

[gar]

161227-1026 EST

iwire:

If I assume that the only buttons and lights are what are shown in your first post, and I use combinatorial logic in a design, then I might design in the following way:

1. I don't know what jog forward and reverse are for. There is no Manual-Auto selector switch.

2. If the elevator is home (down position), and a pallet has been loaded (probably photo detected), then an automatic cycle is started by pressing the Cycle Start button that will take the pallet to the unload position. Note: I really don't care whether the previous pallet has been unloaded. If a sequencer was controlling this system, then an unloaded condition might be required.

3. Something moves the pallet fully on to the elevator. Something detects that pallet is fully on the elevator, and this may include a time delay. If the transfer is by a pusher, then we may need to know that pusher is at least partially returned before the elevator can be started up.

4. Upon the correct conditions the elevator automatically goes from home to its top position. This is an operation that really does not care much about anything else other than that the pallet is correctly on the elevator, and any actuators have been returned.

5. When the elevator reaches its top position, and possibly a time delay, and there is space for the pallet to unload, then some actuating system moves the pallet to the unload position. Note: the system would stay in this elevator top position until the previous pallet had been unloaded.

6. When the pallet has fully left the elevator, then the elevator automatically returns to its home position.

7. A pallet can remain in the unload station as long as anyone leaves it there. It just has to be gone before another pallet can be moved into the unload station. A new start cycle can be initiated as soon as the elevator reaches its home position.

A crude sequencer setup might require that the pallet be removed from the unload station before the next start cycle could be initiated.

.

 

[Jraef]

I'm thinking it may indeed just be as simple as the "Light/Dark" selector operation. There is a little sliding selector switch on the top of the photo-eye, just to one side of the LEDs. If you still have the old one, look at the position of the switch and make sure the new one matches. Or, just try swapping the position, see if it makes it work.

The other possibility is the diferrence in the PNP/NPN issue, which is in effect like NO or NC. This unit provides both and you chose by which terminals you connect to. But if you used the 8 pin micro-connector it came with and did not change any wiring, that should not have been an issue.

 

[iwire]

I'm thinking it may indeed just be as simple as the "Light/Dark" selector operation.

Bingo, as was suggested earlier in the thread this was it.

As far as I can tell with the limited info I have the machine is now all set.

 

[MattS87]

Bingo, as was suggested earlier in the thread this was it.

As far as I can tell with the limited info I have the machine is now all set.

Glad to hear it was that simple. Funny how easy it is to miss that darn switch when you look right at it while adjusting the sensitivity huh?

 

[iwire]

Glad to hear it was that simple. Funny how easy it is to miss that darn switch when you look right at it while adjusting the sensitivity huh?

Well, I did not open the plastic cover, I compared the old to the new and could see that both sensitivity pots were set the same so I put it in place. Never noticed the LT/DK switch.

But thanks, I still wish I knew how it is supposed to work but as far as I know I am done with it.

I am hearing they may scrap it due to the bad bearing and shaft I brought to their attention.

 

[K8MHZ]

Bob,

Did you do the Happy Dance when you got the conveyor running? I am going to want to bet that is a load off your shoulders. Thanks for letting us know what you found.

 

[Jraef]

Glad it was that simple!

 

[iwire]

Are the HVAC / refrigeration 'PLC's you are working on 'Einsteins' or the like? If so, you will find them quite a bit different from an A/B PLC. The techs I worked with that programmed the Einsteins didn't even call them PLC's.

Sort of like the processor and firmware of a VFD. It has a fairly specific purpose and the program is not going to be easily changeable. It may have user parameters that can be changed but the base program is still pretty fixed.

I will stick with 'fixed purpose PLC' so while I agree with kwired to some extent it is much more powerful and versatile than a VFD. Typically I am working with Danfoss http://refrigerationandairconditioning.danfoss.us/home/#/

These are stand alone controllers networked to other remote mounted components that can handle 100s of inputs and outputs of various types.

The big difference I see between these and industrial PLCs is the easy to use interface that is firmware. It is like a PLC with training wheels built in.

When it comes time to add something to the programing like say another refrigerated case it will walk you through it making many choices for you but always the option for customization.

You can go a deep as your skills allow, but the reality is there is almost nothing you would need to do that it does not know how to set up already. From dimming the lights at closing, to running heat reclaim systems etc. to humidity levels, various alarms, exercising generators, recording the pulse meter signals from the utility meters to watch power consumption. Pretty much any thing to do with a supermarket.


If you think about it a modern fire panel is really another type of fixed purpose PLC. You have inputs and outputs only linked by and controlled by software following the instructions provided.

 

[K8MHZ]

I will stick with 'fixed purpose PLC' so while I agree with kwired to some extent it is much more powerful and versatile than a VFD. Typically I am working with Danfoss http://refrigerationandairconditioning.danfoss.us/home/#/

These are stand alone controllers networked to other remote mounted components that can handle 100s of inputs and outputs of various types.

The big difference I see between these and industrial PLCs is the easy to use interface that is firmware. It is like a PLC with training wheels built in.

When it comes time to add something to the programing like say another refrigerated case it will walk you through it making many choices for you but always the option for customization.

You can go a deep as your skills allow, but the reality is there is almost nothing you would need to do that it does not know how to set up already. From dimming the lights at closing, to running heat reclaim systems etc. to humidity levels, various alarms, exercising generators, recording the pulse meter signals from the utility meters to watch power consumption. Pretty much any thing to do with a supermarket.


If you think about it a modern fire panel is really another type of fixed purpose PLC. You have inputs and outputs only linked by and controlled by software following the instructions provided.

Good point about the fire panels. Is 'fixed purpose PLC' one of your terms or is it part of a lexicon that I missed out on? I have never heard it before, but it makes sense. Kind of like 'specific purpose PLC', which is just off the top of my head.