awrobinson
Member
This is my first, and I hope my last, S5 project. I'm not sure, but I think I have died and went to PLC hell.
I am trying to count the falling edge of an input.
I am working on a cut to length project with 3 different lengths cut from long to short, 1 of each and then starting over.
The material advances on a belt through 3 sets of fiber optic eyes, 1 for each length.
I need to count the part entering the eye on the rising edge with 1 counter and count the part as it exits the same eye on the falling edge with another counter, so I can use the math comparisons to determine which set of eyes makes the cut and which sets are ignored. This is probably more info than needed.
I have submitted my question to Siemens Tech Support several times with pretty much a good luck with that.
I have found in the manual an example of a rising edge detection example, but no mention of the falling edge.
Is there any old schoolers out there that can give me a ladder example of a way to accomplish a falling edge detection with a plc that doesn't offer one. I have tried a few things with a normally closed contact, but I get a count on start up, and I don’t want that, I need a count only after the part has entered and exited, not ant time the eye is empty.
I enjoy your forum and thank you for any help.
I am trying to count the falling edge of an input.
I am working on a cut to length project with 3 different lengths cut from long to short, 1 of each and then starting over.
The material advances on a belt through 3 sets of fiber optic eyes, 1 for each length.
I need to count the part entering the eye on the rising edge with 1 counter and count the part as it exits the same eye on the falling edge with another counter, so I can use the math comparisons to determine which set of eyes makes the cut and which sets are ignored. This is probably more info than needed.
I have submitted my question to Siemens Tech Support several times with pretty much a good luck with that.
I have found in the manual an example of a rising edge detection example, but no mention of the falling edge.
Is there any old schoolers out there that can give me a ladder example of a way to accomplish a falling edge detection with a plc that doesn't offer one. I have tried a few things with a normally closed contact, but I get a count on start up, and I don’t want that, I need a count only after the part has entered and exited, not ant time the eye is empty.
I enjoy your forum and thank you for any help.