weird i/o error ! ! !

[rbbalaji]

Hi Guys,
I was rebuilding an old fixture and I have encountered this strange problem. When I connected the sensors, the sensors were showing weird signals. That is part present if no part is present, when I used the ground in the DC power supply(AC to DC). I was frustrated and removed the ground and added a DIODE acreoss the output and all seemed well. Until this morning when I turned the system ON I encountered this ERROR in the PLC and when I connected the hand held it showed an I/O ERROR. Then I turned the system ON and OFF several times until the ERROR disappeared. And now after everything seemed fine I was just testing the fixture this evening and after about 20 trials this problem occurred again. And I turned the system ON and OFF but it was of no use until I pulled out the pressure. Then I turned it ON it is fine now. But I am worried that this should not occur during production time. What should I do.
By the way the input is 24VDC and two of my utputs are 24VDC and one is 110VAC. Please help me out.
Thanks,
Balaji

 

[rbbalaji]

by the way the PLC is an OMRON CPM1A 30CDR.

 

[Mike]

By the way the input is 24VDC and two of my utputs are 24VDC and one is 110VAC. Please help me out.
Thanks,
Balaji

"by the way the PLC is an OMRON CPM1A 30CDR".

Balaji,

I am not sure if you are stating that some of your inputs are 120VAC and 24VDC or if you are using mixed outputs. This is a DC ONLY INPUT UNIT, if you are placing 120V on a 24V input, then this is more than likely why you are getting errors. Use an interposing relay and your problem should go away if this is the case.

If you are using mixed output voltage make sure that you do not have the commons mixed on the relay outputs. If you do then you could be getting a back feed causing an error.

Mike

 

[rbbalaji]

Hi Mike,
I am using 24DC INPUTS only. No mised INPUTS. But like you said I am using mixed outputs.I have to check whether the commons of the relay outputs are mixed, but if you could explain me more clearly what do you mean by mixed common I would be thankful.
Thanks,
Balaji

 

[Mike]

Make sure that your relay outputs are isolated. For example some of your outputs are grouped and have one common for several outputs, if you have the 24VDC and the 120VAC outputs on the same relay output group this could cause a problem. Make sure that the 24VDC outputs are using one common and the 120VAC is using another common.

Mike