One input X0 every time trigger different output alternatively Y0 and Y1

[Jack2809]

Hi i would like to ask!
Im using Omron CP1E PLC
May i know how to use one input to trigger two outputs alternatively?

Meaning press X0 on, Y0 will on, Y1 is off. When X0 released Both off.
Then press X0 once again Y1 will on, Y0 is off
When X0 released both off
Process repeats alternatively for every input of X0
Please guide

 

[IO_Rack]

You are looking for a Toggle Circuit. You should be able to find many examples with a quick search. The PLC brand does not matter.

Post back if you have trouble.

 

[Ken Moore]

Search for flip/flop logic.

Or, since this sounds like a class assignment. Show your work and we will help you learn how to do it, instead of copying someone else.

I'm sure there are more eloquent approaches, but assuming your Omron PLC has rising edge logic, this can be done in three, easy to understand rungs of logic.

 

[Bit_Bucket_07]

The first thing you'll want to accomplish is detecting when Input X0 transitions from off to on and on to off. Different PLCs use different methods to provide for creating a single scan pulse when a rising or falling transition of a particular bit occurs. In Ladder Logic, some use a special output function called a 1-Shot coil. Some offer low to high and high to low transition contacts. Even if your PLC doesn't provide transitional functions in it's instruction set, it's possible to create a 1-shot circuit with basic Ladder Logic functions. Here's an example roll-your-own 1-Shot for a rising edge transition that assumes synchronous IO updates:



Once you have created a means to detect when X0 transitions on or off, you'll be well on your way to writing flip/flop logic that meets your stated criteria.

 

[Jack2809]

Some PLC have ALT function block which works to give alternate output Y0 and Y1, but Omron dont have such function can guide me with PLC sample in how to switch output Y0 and Y1 everytime X0 is triggered

 

[Ken Moore]

What have you tried so far?

 

[drbitboy]

• Have you found a toggle/flip-flop/alternating circuit yet?
• Do you know how to detect the difference between
  • whether the value of X0 has transitioned from 0 to 1, or from 1 to 0, on a single scan cycle, and
  • the level of X0's value (0 or 1) on every scan cycle?
• Do you know how to keep track of whether Y0 or Y1 was on most recently for scan cycles when X0's value is 0?
• Do you know what a scan cycle is?
• Do you know that the PLC is a discrete device?

 

[TheWaterboy]

A counter works if you use bit zero of the .acc as your output.

 

[drbitboy]

A counter works if you use bit zero of the .acc as your output.

Ooh, sweet, especially for this application!

 

[parky]

Yes a counter is probably the best although it could be done with simple logic here is one with a counter

 

[drbitboy]

And I offer this, not as an improvement (because it's not*) on @TheWaterboy's and @parky's most excellent solution, but rather to get OP thinking about the different ways this could be done.

​

* this is not an improvement, nor should it even be in production, nor turned in for an assignment, because @parky's solution is easier to read and understand, while this requires thinking more deeply about the internals of the CTU to understand why it works.

 

[Ken Moore]