Direct Soft Programming Software Question. . .

[rowdyfan18]

Hi everyone. I have a question and while I feel the answer is right in front of me - I am still struggling with it. Anyway, I am working with the Direct Soft Software (programming a KOYO DO-06DD1-D). I have tried to isolate this issue to 3 simple rungs of ladder and my "problem" is still there.

My question is this: If rung 1 consists of a N.O. contact (start) going to a "SET (C0)" . . . . and rung 2 has a "C0" N.0. contact going to a generic output coil (Y0) for a light bulb. . . rung 3 has a N.O. contact (reset) going to a "RST (C0)" = = = = why is rung 3 on ALL THE TIME? It is highlighted blue when the reset button (the only N.O. contact on this rung) is open.

I am not a seasoned programmer. I have worked with AB in the past and it seems to me that the Latch/Unlatch in their software were a little easier to follow. In my little mind I was thinking that when you press the "start" in rung 1 the "SET" for "C0" would energize and would stay energized until you pressed the "RESET" in rung 3 but I am obviously missing something.

Any tips would be greatly appreciated!

Thanks everyone

 

[keithkyll]

Not sure, but my thinking is, it shows the current status of the coil.
When C0 is On, the coil in the SET rung will be blue. When it is Off, the coil in the RESET rung will be blue.

 

[milldrone]

rowdyfan18,

Depending on which AB platform you use you might get the same results.

If the inputs to rungs 1 and 3 are both on this becomes a scan order issue.

I suggest you read this thread by Ron Beaufort. It has to do with the retentive nature of AD vs AB "latches"
http://www.plctalk.net/qanda/showthread.php?p=71786&postcount=1

Then I suggest you click on Ron's PLC bootcamp link by his signature. This will lead you to some sample lessons He has on Youtube. In the sample lessons He will point to how the inner workings of a PLC work.

 

[rowdyfan18]

Thank You

 

[Tom Jenkins]

And this is one reason I avoid set and reset commands. It is much simpler to debug normal coils and contacts. In this case one rung with a holding contact would do the job and the action of each contact and coil is obvious.