Parallel branches

DispensaYEmpaca.Com · Sep 8, 2018

Does anyone finds any benefit on having bit B_10.14 repeated on so many rungs instead of having just one single rung unlatching all these outputs in parallel branches including the MAFR?

Thanks for your comments.

DispensaYEmpaca.Com · Sep 8, 2018

Doesn't this many rungs add clutter to the logic?

Steve Bailey · Sep 8, 2018

When using Latch instructions many people like to see the logic to unlatch a bit in the same place as the logic to latch it.

Aabeck · Sep 8, 2018

I worked on a PLC 5/30 that was so full an online edit terminated & went offline.

I did some experimenting and found out that if I wrote lines as your example is, instead of multiple branches latching one output, that each branch changed to a separate line opened a couple words of memory - I was able to go through the entire program (offline of course) and open almost 1K of memory.

Also, it might just be someone was not experienced or comfortable using branches.

GaryS · Sep 8, 2018

I assume that you re using Logix5000
Way to cluttered all of it could be in 2 rungs
several different ways with far less clutter
a masked move would simplify it

DispensaYEmpaca.Com · Sep 8, 2018

Thanks all!!!

AustralIan · Sep 9, 2018

A masked move would simplify it for us programmers.. but try troubleshooting that thing!
I think having all the logic that effects a bit in the one place like in the original post is ideal.
If I wanted the bits to turn off on power loss /transition to run, i would change it into an OTE seal in circuit, rather than two separate destructive instructions.

Aardwizz · Sep 9, 2018

Personally, I would have written the code as:

      B_11.0   B_1021.3

---+---| |--------(L)---+--

   |                    |

   |  B10.14   B_1021.3 |

   +---| |--------(U)---+





      B_11.1   B_1021.4

---+---| |--------(L)---+--

   |                    |

   |  B10.14   B_1021.4 |

   +---| |--------(U)---+

just to enforce the grouping (Rungs 39 and 41 are identical, for example).

But that's me. Every programmer sees the task at hand differently, and sometimes even differently on different days. It's all a matter of style.

"De gustibus non est disputandum"

damica1 · Sep 9, 2018

Aardwizz said:
Every programmer sees the task at hand differently, and sometimes even differently on different days.

This is Soooooo true!!

Firejo · Sep 9, 2018

Although very close they will unlatch in order as apposed to at the same time.

Parallel branches

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