Hey guys back again with a new probelm.

A machine stopped working on me today whats happening is that a dosing unit isnt getting a signal to run there is a proxy sensor which detects cans and when it sees a can it is supposed to start the filling and no can then no fill. I have checked out the sensor and it is giving an input to the PLC just fine but i am not getting an output! From what i saw before i called it a day is that the output is switching on a relay which in turn is giving a signal to run a 3 phase inverter which runs the dosing motor. I have measured the output voltage and i am not getting any at the plc where i thought the output fuse may have gone, but still nothing. I have also tried to force the relay on manually and nothing happens. The rest of the machine runs ok as it should and from what i can see there is no other limit or position switches on the doser or other conditions that need to be met ie home position, or anything else. Getting no errors on the PLC or anywhere else at the machine, and most importantly i DO NOT HAVE SOFTWARE FOR THE PLC TO CHECK OPERATION. So short of this what else can i do ? The PLC is OMRON SYSMAC CPM1A

 

and most importantly i DO NOT HAVE SOFTWARE FOR THE PLC TO CHECK OPERATION. So short of this what else can i do ? The PLC is OMRON SYSMAC CPM1A

For rapid trouble shooting, monitoring S/W is a must, then next best thing is a hard copy ladder listing showing the I/O addresses etc and check any active items shown in the most likely rung(s).
Any thing short of this is all guess work.
I believe you can download a 30day version free.
Max.

 

Is the PLC output LED coming on?
Is the relay (the one you forced manually) coming on when it's supposed to?
If you forced the relay and it still didn't work, then that should point to something other than the PLC as the cause, correct?
It is hard for me to say without seeing the drawings

 

I would have thought that if it were past the relay, you would at least see it pick up without forcing it and then see nothing further happen?
Max.

 

The pictures in the manual that I found are terrible. It appears that there are output indicators.

That will tell you real quick where to look.

 

If you can bypass the PLC output relay and the motor still doesn't turn on either you have a problem elsewhere or there is a second interlock in series with the motor control systems.

I would suggest working backwards from the motor controls to find where the signal to activate the motor is stopping.

Start at the motor contactor and supply power directly to its energizing coil. If that pulls in its working then follow the power circuit to that coil to find what activated it and so on. At some point you will find one or more relays that have to be activated for it all to work and if they get their power directly from the PLC outputs then you have to look at all the PLC inputs that have say in things.

Personally I find PLC trouble shooting to be a love/hate concept. Either it's a system with a design you can relate to and it's an enjoyable logic puzzle to work on or it's not.

 

The pictures in the manual that I found are terrible. It appears that there are output indicators.

That will tell you real quick where to look.

There are both input and output indicators, but this does not tell you what is happening in the Boolean logic string?
Just inform as to the status of I/O.
Max.

 

If you can bypass the PLC output relay and the motor still doesn't turn on either you have a problem elsewhere or there is a second interlock in series with the motor control systems.

.

But I come back to the fact that if the output relay is not picked up, and should be, then there is a concern with the internal logic.
The bottom line is monitoring S/W is a must IMO.
This makes trouble shooting a breeze and that was/is the original intention of the PLC.
Max.

 

But I come back to the fact that if the output relay is not picked up, and should be, then there is a concern with the internal logic.
The bottom line is monitoring S/W is a must IMO.
This makes trouble shooting a breeze and that was/is the original intention of the PLC.
Max.

I agree.
I have experience with this PLC and it is an arcane P.O.S.
The software you need is Omron SYSWIN. It's also a P.O.S.
I believe you can download it for free if you can find it still. Last rev was in 1999.
It won't run on anything newer than winXP.

 

It's been quite a while since I played with a PLC. I don't recall the OP stating whether the output indicator was on or off.
It would be nice to know.

If the output indicator is off, when it should be on......I would suspect that you are not getting all the required inputs to latch. Check all required inputs states. The OP stated that as far as he could tell, there was no other input requirements. Therefore, I would suspect a timer on the latch to control dose rate. Confirm this setting. We don't want this on 1 ms.
If it still does not output.........check hardware on I/O board. I would suspect a PLC software problem last. Other than entrant setpoints.

If the indicator light is on........check output voltage at PLC. If zero.....pull lead and check again. If you get normal voltage with output dis-connected.......re-connect output and go to inverter relay and dis-connect there. Measure voltage. If you get voltage, your control line is good........check inverter relay.

 

The OP stated that as far as he could tell, there was no other input requirements. .

Very difficult to know without a ladder listing!
Max.

 

i agree Max absolutely but i also forgot to mention that i dont have the program for this PLC as the machine was bought overseas at auction and anyone involved in it has long since retired and cannot be contacted. I have been thinking that if i force the output on by giving it 24volts this should power the relay and in turn run the inverter this would at least eliminate the inverter, relay and motor side of things right??


cheers for all the input dudes

 

If the 24v is connected to a external relay could could test by disconnecting from the PLC and applying the coil voltage.
Take care other safety features would not be over-ridden.
If you can obtain a copy of the software you would at least have a listing, even without any other documentation it would be helpful.
Max.

 

but i would still need the program to see whats going on wont i?

 

The S/W would enable you to not only monitor the existing system in real time but down load a copy.
At least if Omron conform to the typical S/W format.
Max.

 

Ah excellent thanks guys

 

The S/W would enable you to not only monitor the existing system in real time but down load a copy.
At least if Omron conform to the typical S/W format.
Max.

Yes the SYSWIN will allow you to download from the PLC but with no comments. Your ladder program will have only bit addresses. But with a bit of time devoted, you can add your own comments

 

Yes the SYSWIN will allow you to download from the PLC but with no comments. Your ladder program will have only bit addresses. But with a bit of time devoted, you can add your own comments

Is any custom cable required for Omron?
Max.

 

Is any custom cable required for Omron?
Max.

yes I believe so. I found this:

 

Good thing the CPM1A does not use the same programming interface as its predecessor. The C200H requires a serial BOX (LK201 Host Link adapter) to be bolted to the front of the PLC in order to communicate with a PC:

This thing was a serious P.O.S.
Few people have them anymore, they fetch a good price now.