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Old October 5th, 2017, 01:10 PM   #1
backendcode
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can not turn on the motor with PLC

Hello Guys,
This is my first PLC project of the conveyor system. I am trying to test my code and turning on my motor with start button on the control panel. When I press the start button, I can see motor output bit 1 but my actual motor does not start.

I attached electrical circuit of a motor and my PLC code. Please someone can help me if I am doing something wrong.

https://ibb.co/dch0WG (electrical schematic of motor)

https://ibb.co/h9cpQb (PLC code)

Thank you,
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Old October 5th, 2017, 01:17 PM   #2
jstolaruk
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Is the s/w routine that that the rung of code is in actually being executed?

Grab a volt meter. Does the motor contactor energize? No? Is the MOL tripped? Reset it. Do you have a control voltage at the PLC output when it is activated? No, check the power common to the output module. Yes? check for voltage between the MOL and contactor coil.

Diagnostics is just a matter of eliminating things that can go wrong.
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Old October 5th, 2017, 01:20 PM   #3
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Does the LED indicator for the PLC output card light? If no, look at your software. If yes, check electrical items, connections, etc.
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Old October 5th, 2017, 01:27 PM   #4
LoganB
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Most common mistake in a situation like this is a missing JSR in your main routine
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Old October 5th, 2017, 01:41 PM   #5
backendcode
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Quote:
Originally Posted by jstolaruk View Post
Is the s/w routine that that the rung of code is in actually being executed?

Grab a volt meter. Does the motor contactor energize? No? Is the MOL tripped? Reset it. Do you have a control voltage at the PLC output when it is activated? No, check the power common to the output module. Yes? check for voltage between the MOL and contactor coil.

Diagnostics is just a matter of eliminating things that can go wrong.
When our maintenance guy manually pressed the contactor, it turns on the motor which means motor overload is not tripped ( i guess) and when I turn on the output bit of motor with PLC, I can see my output card show an indicator light but my contactor doesn't energized!
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Old October 5th, 2017, 01:41 PM   #6
backendcode
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Quote:
Originally Posted by LoganB View Post
Most common mistake in a situation like this is a missing JSR in your main routine
i am testing this program so everything is in main program. it just two line code which attached in starting thread.
thank you
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Old October 5th, 2017, 01:43 PM   #7
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Test the contact on the PLC output card to make sure it's actually energizing. A bad output could fail to close the contact even if the light turns on. If you get your current reading, then check the other end of the wire to make sure you don't have a broken wire. Just keep moving one step down the chain with your meter until you figure out where it stops. That should pinpoint the problem.
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Old October 5th, 2017, 01:48 PM   #8
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Quote:
Originally Posted by LoganB View Post
Test the contact on the PLC output card to make sure it's actually energizing. A bad output could fail to close the contact even if the light turns on. If you get your current reading, then check the other end of the wire to make sure you don't have a broken wire. Just keep moving one step down the chain with your meter until you figure out where it stops. That should pinpoint the problem.
I agree but How come when Maintainace guy manually press with contact, it turns on the motor? if wire is broken, it should turn on either way (i guess)
thanks
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Old October 5th, 2017, 01:49 PM   #9
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Personally,

I would break the code up in to these routines.
Input
Motor
Output

I don't like mapping IO around in the actual code. Then you should be able to see if the code is actually trying to turn the output on or if the code isn't working.
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Old October 5th, 2017, 01:52 PM   #10
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Well, what have you done to troubleshoot the electrical part of it? Are you a qualified electrician? I mean, do you know enough not to smoke yourself?

The code seems fine.

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Old October 5th, 2017, 01:53 PM   #11
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Quote:
Originally Posted by backendcode View Post
I agree but How come when Maintainace guy manually press with contact, it turns on the motor? if wire is broken, it should turn on either way (i guess)
thanks
The maintenance guy is performing the function of the coil. So everything in the coil circuit is suspect, all the way back to the s/w.
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Old October 5th, 2017, 01:54 PM   #12
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what output card are using, and can you show us the wiring for it? can you take a voltmeter to the output what is voltage shown?
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Old October 5th, 2017, 02:01 PM   #13
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I electrical diagram I attached! To turn on my motor, I need to set 1 to my output card address R1S5DO01 right?

https://ibb.co/dch0WG (electrical wiring diagram)
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Old October 5th, 2017, 02:23 PM   #14
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The output card needs to be the correct type. They make AC/DC volt/current output cards, but that motor contact is looking for one specific type. Probably either 120 AC or 24 DC, but I wouldn't be surprised if there are others out there. Was the card chosen by someone that has experience with this sort of thing?

The PLC output is just sending a signal to close a contact on the motor and allow it to receive the higher voltage power to run. The output isn't supplying the power to run the motor. Manually closing the contact doesn't verify whether or not the signal from the output card is reaching the contact.
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Old October 5th, 2017, 02:45 PM   #15
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Quote:
Originally Posted by LoganB View Post
The output card needs to be the correct type. They make AC/DC volt/current output cards, but that motor contact is looking for one specific type. Probably either 120 AC or 24 DC, but I wouldn't be surprised if there are others out there. Was the card chosen by someone that has experience with this sort of thing?

The PLC output is just sending a signal to close a contact on the motor and allow it to receive the higher voltage power to run. The output isn't supplying the power to run the motor. Manually closing the contact doesn't verify whether or not the signal from the output card is reaching the contact.
Please check this link

https://ibb.co/nr2Okb

Can you please explain me what is this? When I puss this to 1, then my PLC code work and it turn on the motor. how can I pull in with PLC code?

I think my NC estop energizing this device? i guess? Because there is label on this device CR60044 AND in my electrical diagram, e-stop energized this coil
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Last edited by backendcode; October 5th, 2017 at 02:50 PM.
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