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robh

W coil not working

22 posts in this topic

I have a "W" coil that has my limited Omron brain stumped. When the rung is logically true, the coil has green on both sides but is still grey and not executing. I can force said coil and it executes, and the center turns green. Everything else in the file appears to be working fine. I have even built a duplicate rung at the bottom of the file that is exactly the same but the "W" address is different and it executes fine. What am I missing? Thanks, Rob

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Double post! D'oh! Silly Android phone.

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Some other rung in the software turning it off?

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Not that I can find Bob. Xref only shows that address in two places, the coil and one n.o. contact on the next rung.

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Does the program in the Plc match the program in the pc?
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Yes blue. I compared and downloaded multiple times to check.

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1: No interlock (IL) instruction before it? 2: No value written to the "W" word that contain this "W" bit? ( MOV instr., etc...)

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Not that I could find pfort. I dumped a clean program in and problem went away. I think it might if had something to do with me putting a contact into a function block, well that's the best I can come up with. New logic in and working fine. Forward ho!

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Posting the code helps everyone here more to evaluate what is happening.

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I agree lost, but my employer has rules against it.

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Which model PLC??? Are you using multiple TASKS in your program structure?? Do you have the W Coil in a separate TASK?? If yes then is that task enabled. Tough to help without the code.

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We hear this all the time, but of what use is the code to us if we do not know what your process is? You can always strip it down so that only relevant parts are posted, or even PM it to someone..
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First off, thanks for the effort to help. I understand it is difficult to help someone without the code who isn't asking the question very well. But as long as want to be an employee here I will follow their rules. Programming software: CX-Programmer Ver.9. 4. 0. 7 PLC: CJ2M-CPU33 So I will try again: What is the difference between a coil that is all green with green rungs on both sides and a coil that has green rungs on both sides but is gray in the middle? All logic in front of this coil is true. Thanks, Rob

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You mean as attached? You can see that there is double-coil syndrome... The last one wins Edited by lostcontrol
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The same will happen if the Plc and pc don't match, or if the Plc is in program.Hope this helps.
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Also, comparison flags like P_EQ, P_LT, etc can cause this as the same comparison bit is used many times in the program. It can cause some strange "looking" things to happen. It still works fine, but looks wrong. See the attached pics. The P_EQ flag is true for the last rung (red arrow), so the P_EQ bit shows as being on. However, when rung 1 was executed in the scan, the P_EQ bit was off, so the coil (blue arrow) was off even though the last state of the bit was true. So, check for comparison flags to be the cause. The below condition could also happen. Coil is on, but the contact appears to be off. As others have suggested look for IL, ILC functions and JMP, JME functions.

 

post-19500-0-79087700-1345688689_thumb.jpost-19500-0-08379100-1345688846_thumb.j

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Thanks for the ideas. I still have absolutely no idea what was going on and I haven't been able to recreate "my problem". I think that it might have been something like what bluebyu suggested. So forward we go. I have just spent the last month converting a TCP touchscreen to an Omron NS10 connected to a C200H. Starting to flow a little better through the Omron stuff now, even kind of like it. Thanks, Rob

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I know that this might sound stupid... but when the PLC is in program mode... the code in front ie contacts etc can show the on state green (as they should if on in the real world) yet the coils will be off that use standard IO and W words as they are non retentive..
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Hi Always check that your code is executed IL END ect. Put in at instruction with the same conditions as your coil: +F Dxxx +1.0 Dxxx Banker

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Any chance your W bit is mapped to an input somewhere (Devicenet, Profibus...)? Happened to me once. Contractor fat fingered something and moved half the I/O table. First symptom was work bits that weren't working.

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Create a dummy coil parallel to the problem one. If it dos not work either, try to turn it On/Off from CX-Programmer. If able to, the code is not being executed. Otherwise, the problem is in the rung conditions,. Edited by Sergei Troizky

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A few other cases where you would see this. 1. The code is in a Task that is not running. 2. The code is in a subroutine that is not being used. 3. The code is in a section that is after the END statement. 4. The code is in a section that is after subroutines (like below) <code section> <code section> <code section> <subroutines> <code section> <END>

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