One Shot Instruction

Hello everyone,
I am a beginner in PLC programming and I need your help. I am trying to use a one-shot instruction in my program just to see how it works but the challenge that i have is that when I actuate my n/o input and click on 1 scan the one shot is actuated ()turns green on the first rung but on the second rung nothing is happening. My second rung has two instructions, it has one n/o input with the same OSR address (A/0) and output O/1. I thought I was supposed to see the input & output on the second run activated. Am I missing something? Thank you...

Can you post the code?

One shot should only be active for one scan, so if it's part of an output you'd see it go on and immediately off. (realistically you wouldn't see it change state)

Try this arrangement and see if you get a different result.

Rung 1:NO input, OSR, Latched Output.
Rung 2: Different NO input, Unlatch for the Output on Rung 1.

This should give you a better idea of how the OSR behaves.



Bubba.

If you are using Rockwell Software, look at the ONS instruction, instead of the OSR. When I started out, I started with the OSR since it seemed easier to understand and utilize than the ONS, however i quickly realized that a ONS was the way to go, for me anyway. With a ONS you don't need to create any extra latch bits or worry about storage bits etc. Not sure if that suits your ladder logic but just a shot in the dark. You basically place the ONS right after all input instructions on the rung and then all the outputs (branched or not) you want to one-shot are placed after it on the same rung.

AB implements the "OSR" instruction differently depending on the PLC you are using.

What is the model of PLC you have?

If you can, post a screen shot of the 2 rungs in question.

See pdFS

If its osr2 then you will need a different address for that OSR (same as an "ONS) instruction in rung 2.

finally got it...

Hello guys, thank you so much for the comments, they were really enlightening. I managed to get the program for the ONS, OSR and the OSF running properly. I am grateful for all the information you have shared!