Negative edge detection

danielchen · Jan 28, 2016

Hello every body!!!

We have siemens s7200

Iam trying to detect the relise of the push botton.
That is to say the transiation of 1 to 0.

I have wrote the botton script like at the pic.
But change the m149.5 to (s)
And as soon as i push the botton
Even before relise the set is change status to work.

Why??
Is that the way to detect a falling edge??
Do i have to change the progrm.

Thanks a lot in advance.
Daniel

TurpoUrpo · Jan 28, 2016

That is not from s7-200.

Usually with push buttons there is a possibility of it flickering (remember, plc scan is lot faster than you seeing the led go on..) while the push is being executed by your finger. Try using timedelay on the "on" state before falling edge detection.

dwoodlock · Jan 28, 2016

It looks correct to me, when you release I96.3 as long as the physical contacts are NO, then you will set M149.5

I typically dont use the negative (or positive) transition bit in multiple places, but thats your call.

bkottaras · Jan 28, 2016

danielchen said:
Hello every body!!!

We have siemens s7200

Iam trying to detect the relise of the push botton.
That is to say the transiation of 1 to 0.

I have wrote the botton script like at the pic.
But change the m149.5 to (s)
And as soon as i push the botton
Even before relise the set is change status to work.

Why??
Is that the way to detect a falling edge??
Do i have to change the progrm.

Thanks a lot in advance.
Daniel

Try this

Code:

---|PB|-----(P)-----(Pos Pulse)
---|PB|-----(N)-----(Neg Pulse)

PB = Your input
Pos Pulse = Transition from Low to High
Neg Pulse = Transition from High to Low

danielchen · Jan 28, 2016

dwoodlock said:
It looks correct to me, when you release I96.3 as long as the physical contacts are NO, then you will set M149.5

I typically dont use the negative (or positive) transition bit in multiple places, but thats your call.

Can u please correct the program like u suggest.
In the lad language not stl or other.
Ill be much thankfull to u.

I like to heare what is u way too

Thank in advance.
Daniel

danielchen · Jan 28, 2016

dwoodlock said:
It looks correct to me, when you release I96.3 as long as the physical contacts are NO, then you will set M149.5

I typically dont use the negative (or positive) transition bit in multiple places, but thats your call.

Can u show me ,u way.
If u can show U program ill appriciat it

danielchen · Jan 28, 2016

bkottaras said:
Try this

Code:

---|PB|-----(P)-----(Pos Pulse) ---|PB|-----(N)-----(Neg Pulse)

PB = Your input
Pos Pulse = Transition from Low to High
Neg Pulse = Transition from High to Low

What is the deference between u suggestion to my.
I dont see a difference.
Mabe because iam not familier with the code like u do.
Thanks

danielchen · Jan 28, 2016

danielchen said:
Can u show me ,u way.
If u can show U program ill appriciat it

I think again mabe i wont change the address (m149.5)
And i use it as follow to turn on the (S)
----Im149.5I-------(S)
What u think.ill check that on next tuseday.

dwoodlock · Jan 28, 2016

here, basically what you had but with a set at the end.

danielchen · Jan 28, 2016

Thans ill try it

Negative edge detection

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