output signal

kemp40 · Jul 21, 2016

Hi!
my directional valve double solenoid for hydraulic cylinder
using PLC micrologix 1500
i give close command my cylinder close and open by it self
observing that output signal led indicating both close and open solenoid are energized same time!
could it be a PLC program issue?
(we have replaced new directional valve, oil, and limit switches)
please any one can help me to solve the problem
thanks in advance.

gclshortt · Jul 21, 2016

Does the LEDs on the output card of the PLC show that both are on. (OPEN and CLOSE) If this is the case then you should look at the PLC logic.
Can you post the part of the program that controls the cylinder?

Regards,

James Mcquade · Jul 21, 2016

How is the valve connected to?
the 1500 or an expansion module?
what is the part number of the device the valve is wired to?

it may be that if this is relay outputs that the contacts are welded together or the contact arms are broken.

are the outputs solid state outputs?

regards,
james

kemp40 · Jul 21, 2016

Please check attached picture for outputs
this during operating to close LED 6 only should lighting.
but 5 (open) also is there, i cannot remove it
kind regards.

kemp40 · Jul 21, 2016

Hi
I not yet have a the program access, the client has took the work station PC
and there is no backup software or program CD.

Tom Jenkins · Jul 21, 2016

If it was me I'd start by putting voltmeters on the valve terminals.

JohnCalderwood · Jul 21, 2016

That is a relay output card, so looks like both outputs are on incorrectly.

You have positively identified that these are the correct outputs?

If you disconnect one output wire from the PLC does the cylinder move in the expected direction?

kemp40 · Jul 21, 2016

We checked all the panel wiring, and even when we disconnect the inputs and outputs led still there.
we replaced also the output relay module no changes.(not the terminal block)
we have checked the entire system valves, limit switches and sensors
i don't know if i miss something.
i would like to tell you that this problem is occurred on 2 other units
this fault happening only on the same component all other hydraulics, pneumatic are working fine.

kemp40 · Jul 21, 2016

Yes, like you said we disconnect and also we place a manual switch on a junction box and i was able to control the cylinder at all positions even mid stroke .

James Mcquade · Jul 21, 2016

2 things come to mind.

#1 the output(s) are forced on.
#2 the programming does not turn off the output logic correctly.
with no program software, you will be waiting on him to correct the problem.

I would get a laptop, software and cables to prevent this from happening in the future, especially if production suffers.

james

AGill · Jul 21, 2016

kemp40 said:
Yes, like you said we disconnect and also we place a manual switch on a junction box and i was able to control the cylinder at all positions even mid stroke .

Sounds like the problem is in the program.

output signal

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