# RS Logix issue



## Mattyw87 (Jan 13, 2013)

Guys,

I recently tried to make a change to my RS Logix program. Currently there is a solenoid valve that is operated as a latch output. I want to leave that there, but I also want to be able to operate that same solenoid valve by other pushbuttons. I built another rung right below my current rung where the latch output is located. Then I put in my inputs and put in a regular output and gave it the solenoid valve address. Now I have this solenoid on a regular output and a latch output. When I tried to run the program my inputs were closing and giving a signal to my original latch output, but it wasn't operating the valve. Can I not use the same address point and have it on two different outputs? What is a good way to be able to operate the same valve with different inputs. Thanks in advance.

Matt


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## SteveBayshore (Apr 7, 2013)

Print the page of ladder and post it.


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## Wire it (Mar 14, 2011)

Instead of creating a new rung, add a branch to the existing rung. Add your new logic/IO to the branch to energize the output either way.


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## Mattyw87 (Jan 13, 2013)

*rs logix*

I thought of just adding a new branch, but if I added a new branch it would be going to the latch output. Then, I may be trying to energize it when the unlatch is energized as well. I don't want to make any changes to the current way it works, I just want to be able to operate this valve on its own. I am trying to print it off to post it, but not sure if I will be able to do this. I may be able to draw it up and post it that way.

Thanks


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## dronai (Apr 11, 2011)

No, I don't think you can do it with a latch (you do mean latch and not seal in) You could only parallel switch the input to the same latch. Because the output address is what is being latched. You probably need it latched so it's retentive.


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## ScooterMcGavin (Jan 24, 2011)

Sounds like you have a classic case of double coil syndrom. Trying to fire an output from different places causes this exact problem. Personally I'm not a fan of latch/unlatch for this very reason. Especially using all three diffrernt coil commands. If you have a start/stop you could us them on the latch/unlatch, but it depends on how he main program unlatches the output. The best way to do his would be to use the OTE and do a seal in circuit. Seeing the code would help me be more specific.


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## JRaef (Mar 23, 2009)

Are you using the latched output so that it retains state after a power failure? If not, why are you using a latched output?


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## 04-20ma (Aug 21, 2011)

Never use multiple output instructions with same output address


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## KennyW (Aug 31, 2013)

04-20ma said:


> Never use multiple output instructions with same output address


This^

If the latch unlatch logic is used consistently throughout the program/site and you don't want to change it to a normal "OTE" with a seal-in, then add a new branch to the OTL rung and put your start conditions in it. If the I/O is mapped then it doesn't matter if you try to latch it when the unlatch is active, as long as the unlatch is below the latch rung (later in the scan sequence) as the bit will be un latched before it is ever mapped to the actual output card address. 

If the I/O is not mapped then you need the take the OTU rung conditions, invert them, and put them into the new branch you made in the OTL rung. Or add an OTE memory bit jn the OTU rung an condition it with that (examine open). Messy. This is why a normal OTE with a seal-in is typically considered better practice. And OTE' and mapped I/O even better. 

Hope this helps. As was said if you post a screen shot of the ladder I sure I or someone else could mark it up for you and it'll make more sense.


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## DHiti (May 17, 2013)

Sounds like double coilitis had taken another victim. KennyW has you on the right path.


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