How do I fix this?

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iwire said:
I have very little PLC experience and none with AB.

The 'operators' are all unskilled temp help, this is not in an industrial location it is in a store.

Thank you for the response.
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allen bradley will support the device, if you can bear to deal with them.
the day before christmas is not, imho, the time to breach their voicemail system.
santa's little helpers over there are most likely on holiday.

i can't tell what micrologix series you have, but i have interfaces for a couple of them.
it's rudimentary PLC, but AB doesn't give anything away. including programming software.
if i have it, and i might, you are welcome to it, but the truth is, if you have to buy it,
it would probably be cheaper, and faster, to buy a cheap plc, that you are familiar with,
program it offsite with the functionality you wish, and install it in place.

i had the controls for a newspaper pressroom that was a similar situation. it was easier
to replace the plc, as it wasn't supported by anyone.

post which series it is, and i'll see what i have.

edit:

seems to be a micrologix 1000. i'll be by the shop later, and see what i have in the bin.
 
jim dungar said:
My guess is that the PLC is 'out of sequence' with the real world. For some reason, these are often hard to re-establish if you do not know the secret handshake.
Heaven forbid, if the original program designer expected this to be job security where they had to be called in for servicing. Proprietary systems are definitely a bad idea when the 'proprietor' is no longer in business.
Any PLC ladder diagram is better than nothing.
Click to expand...
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my gut instinct is there is a shift register in the code,
to track and sequence the product flow, and it's out
of time.

without being able to watch what it does, there's no
way to suggest a fix from here, but if i was there,
i'd draw myself a picture of what sequence of operation
looks like, and figure out how to complete the sequence
it appears to be stuck in....



ohoh. time is running out.... from those fine folks at AB....

Rockwell Automation announces that as of June 30, 2017,
our Bulletin 1761 MicroLogix™ 1000 Programmable Logic
Controller Systems will be discontinued and no longer available for sale.
Customers are encouraged to migrate to the
Micro820® PLC Systems or Micro830® PLC Systems.

http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/migrat-pp012_-en-e.pdf

the migration strategy... ^^^^
 
Last edited:
161223-1338 EST

iwire:

I don't want to go back thru the thread and look at details.

This is what I think I remember:

1. You have a customer with a conveyor system that failed.

2. A person at that store observed that an indicator light on a photo-detector did not light. Thus, assume a photo-detector failed. This particular detector I have called Photo-1.

3. You observed that Photo-1 appeared to not work, and replaced with an identical unit, and adjusted the sensitivity. Changing the state of Photo-1 produced a change in state of the input indicator at the PLC.

We don't know if the phasing is correct. If I were designing the system I would choose the logic so that the LED indicator at the PLC input would light when a package was present at the photo-detector position. For simplicity I would call this logically as True, 1, or asserted. Physically this might be +24, 0, or -24 or other depending upon the system design. Only if there were some fail safe requirement inter-related with the system design would I have the PLC input LED be off for part present.

Indirect information seems to imply that the photo-detector is a simple on-off sensor, no timers. I did not adequately check this via your photo-detector part number. Too hard to read the AB sheet.

So I assume LED lighted at the PLC input means part present, that this is the desired phasing, and that this is what you have observed with the new photo-detector after it was installed and adjusted.

4. After the new Photo-1 was installed and adjusted, then the conveyor was started. A bin passed Photo-1, and something failed when the bin arrived at Photo-2.

I don't know what failed. Did Photo-1 fail? Did the system fail to do what it should when the bin reached Photo-2. Did Photo-2 fail?

What specifically is this conveyor system to do? I see what looks like a current transformer in the photo. From this I suspect there is some sort of overload detection. The only labels I can read are Start, Stop, Waiting to Unload, Jog FWD, Jog REV, Reset. I don't know what the three other indicators are. Are there multiple unload points. How many different photo-detectors? Physically at what point is the unused limit switch and what might have been its purpose?

If there is a motor overload, then I might assume that Reset could at least be used to reset the overload.

Can you provide any information on what the this conveyor is supposed to do?

.
 
Fulthrotl said:
.
my gut instinct is there is a shift register in the code,
to track and sequence the product flow, and it's out
of time.

without being able to watch what it does, there's no
way to suggest a fix from here, but if i was there,
i'd draw myself a picture of what sequence of operation
looks like, and figure out how to complete the sequence
it appears to be stuck in....



ohoh. time is running out.... from those fine folks at AB....

Rockwell Automation announces that as of June 30, 2017,
our Bulletin 1761 MicroLogix™ 1000 Programmable Logic
Controller Systems will be discontinued and no longer available for sale.
Customers are encouraged to migrate to the
Micro820® PLC Systems or Micro830® PLC Systems.

http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/migrat-pp012_-en-e.pdf

the migration strategy... ^^^^
Click to expand...
You can get basic software for the ML1000 only for less than $200.
 
Guys I have not forgotten this just don't have time to get into it on my mobile

Thanks again, I will get back to this Saturday.
 
JFletcher said:
Dumb question, but how do you know that getting it to work will equate to getting it to work safely?
Click to expand...

That particular PLC should have nothing to do with machine safety. It is not a safety rated PLC. The machine safety system should be controlled by another source in this instance.

You never want e-stops, safety limits, light curtains, etc going to a regular PLC for safety purposes. I'll often times run a secondary control circuit on an extra set of contacts from those devices to inputs back at the plc just for monitoring and alarms, but the primary control circuit through them is what actually shuts the machine down.
 
Sorry guys, been busy with Christmas stuff.

I do appreciate the responses and will get back to all that have replied when I can.

Merry Christmas
​
 
mgookin said:
Go buy a cheap laptop at WalMart. Spend whatever money you need to. Do the job and leave the laptop with the manager at the store. He will now have what is necessary to maintain his equipment. Do it all at his expense.
Click to expand...
Bigger issue is the necessary A-B software you will have to install on whatever computer you end up using.
 
iwire said:
Sorry guys, been busy with Christmas stuff.

I do appreciate the responses and will get back to all that have replied when I can.

Merry Christmas
​
Click to expand...


Busy time with family. And Hogmanay is coming up right on its heels.
I was going to say enjoy the down time but it isn't really. Hectic holidays.
 
ptonsparky said:
The older software uses the old 9 pin ports that are no longer on most laptops. The USB to SERIAL conversion from AB was about $450. Worth the money if you have need.
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I sell a brand of USB to serial cable for $150.00 too, but just send folks to Walmart for the $ 6.00 one! Works fine with the AB PLC!

6 pages here and going strong??

Bite the bullet and hire an AB PLC wizard to come diagnose and fix the issue in 1 hour.

Sent from my SM-G900V using Tapatalk
 
mike_kilroy said:
I sell a brand of USB to serial cable for $150.00 too, but just send folks to Walmart for the $ 6.00 one! Works fine with the AB PLC!

6 pages here and going strong??

Bite the bullet and hire an AB PLC wizard to come diagnose and fix the issue in 1 hour.

Sent from my SM-G900V using Tapatalk
Click to expand...
I bought a couple $6 - $20 ones. Inconsistent and would quit in the middle of things. POSs.

ABs 1st time, every time and I would have saved myself hours of frustration because I thought it was me screwing up. Happens often enough without help from poor products
 
Saturn_Europa said:
I just worked on a AB photo eye last week. Ive read that manual you posted and the only part I found useful was this section:






999 time out of 1000 if the PLC is up and running for years and years you can fix the problem without going online with the processor. Its some physical I/O that has gone bad. Of course it makes it much easier to trouble shoot if you can see the logic.


I've seen programmers do tricky stuff with reset buttons also. Sometimes you have to hold down the reset button for 30 seconds before a fault will clear.

I would check all the fuses (Im sure you started there), tighten all wire terminations, and I'd also double check that E-Stop.

Things are a lot easier if there are wiring diagrams. Its probably something simple like a stuck limit switch.


Good luck!
Click to expand...


I agree about the PLC. And other than that one component, and any that need to be replaced, iWire should not be too concerned with a manufacturer of the entire system, unless he happens to be lucky enough to find a schematic, but that is unlikely. It is mostly a matter of process of elimination.

First, make a comprehensive schematic.
second make sure one knows exactly how the system is supposed to work.
After that it is a matter of inputs and outputs
Inputs are either analog or discrete. Discrete is on or off so it is very simple
Analog can be varying voltage or varying amperage.
Same thing with outputs on/off or variable.

From there it is simple electricity.

So get a map of the PLC inputs and outputs. Figure out what input should create what output and use a meter to read the signal.

I know I am oversimplifying it, and this process can take a long time, but that is still all there is to it.
 
ptonsparky said:
I bought a couple $6 - $20 ones. Inconsistent and would quit in the middle of things. POSs.

ABs 1st time, every time and I would have saved myself hours of frustration because I thought it was me screwing up. Happens often enough without help from poor products
Click to expand...

Very valid comments! This too is why we sell a mfgr namebrand one for high dollars for those who have issues making this kind of thing work! If we all just had a 12 year old with us, we could make ANY work! And there ARE counterfeit ones out there where the official drivers won't work. This said, I have yet to not make a cheap one work consistently. (ones that work some but not always often have 16-30msec latency setting - this is in advanced settings and needs to be 0 or 1msec or timeouts CANn happen.)
 
Strathead said:
I agree about the PLC. And other than that one component, and any that need to be replaced, iWire should not be too concerned with a manufacturer of the entire system, unless he happens to be lucky enough to find a schematic, but that is unlikely. It is mostly a matter of process of elimination.

First, make a comprehensive schematic.
second make sure one knows exactly how the system is supposed to work.
After that it is a matter of inputs and outputs
Inputs are either analog or discrete. Discrete is on or off so it is very simple
Analog can be varying voltage or varying amperage.
Same thing with outputs on/off or variable.

From there it is simple electricity.

So get a map of the PLC inputs and outputs. Figure out what input should create what output and use a meter to read the signal.

I know I am oversimplifying it, and this process can take a long time, but that is still all there is to it.
Click to expand...

If they are paying by the hour, and are happy with all this hard work you do, then go for it!

Otherwise, hire that AB PLC wizard to come watch the ladder run and diagnose and solve the issue in an hour instead.
 
Silicon Labs makes the bridge (driver) to make usb to serial work and it's free. I don't understand how there can be a counterfeit of something that's free. Cables are cheap. The hardest part is checking what port picked it up in Device Manager, and that takes all of 10 seconds.
 
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