Brian 20

more than one output?

5 posts in this topic

Im a beginner. 

Is it possible to have an output duplicated in the ladder program. eg output Y1 will appear in 2 places.

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Not good practice.

If you want an actual output to appear in two separate lines of code, put an M relay in place of one and a n/o of the M relay to operate the output

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Hello

As mentioned by Ron it is not a good practice but you can do like this

-----(M1)

-----(M2)

---|M1|---------------(Y1)

---|M2|----

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it depends on what you mean...

when using latch (set/reset) type of commands this is pretty much a must and therefore unavoidable. for example one can have bunch of rungs setting different bits on when faults are detected (first use) and clearing them all when acknowledging (second use).

when using coil type of instructions this is not just bad practice but it will bite back... monitor will show the result of the last used output instruction but value will be affected by both, depending on how the logic is scanned. if the two rungs are just one after another, first one will likely have no effect but - there are exceptions

for example some people used it to break down large simple logic type of rungs (OR or AND).

probably habit from some old platform with limited resources like size of run/network or available memory etc. (like smart relays) or just to make it easier to see the code without having to use bunch of intermediate or temporary flags.

in general it is your sandbox and ... if you really know what you are doing... you can do anything you want. there is a time to follow the rules and time to brake them.

but for the sake of everyone else that is supposed to maintain that code, avoid it. 

here is an example of large rung broken down, without using additional flags, hence duplicate coils. important thing to note is that even if one chooses to do something like this, it is very important to keep track of correct order. or things will quickly turn ugly...

 

 

using_duplicate_coils_OR.png

using_duplicate_coils_AND.png

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Actually when I said bad practice - I did mean NEVER

But as usual, there are exceptions and that's where I meant bad practice.

 

If using mitsi's own brand of drum sequencer STL and you want the same output to be on through several stages, you can double coil through it as only one STL step at a time is scanned.

But that would mean you couldn't use that output outside of the STL sequencer. 

You would use M relays instead of the output and control the output outside of the sequence with those M relays

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