Help for this PLC question(same output used twice)

Hi all!

I have one question, it might be simple for one of you but I spent hours searching and reading through different platform until I found this one.

I wish I can get the answer:
Q. Write a ladder logic program that will cause a light to come on if a
PLC counter value is less than 10 or more than 30?

This is what I came by

https://ibb.co/2nQzSCY
continue

https://ibb.co/Wz3LFGW

I want to know if there is a possibility to use the same output(O2:0) twice since the question asked about a light. Thanx!

Nope.
Use a branch to do the OR operation.

I am a beginner if you can elaborate just more on how to do it, it will be such great help from you.

In the same rung (with branches as needed) you should have two conditions that energize the output.
IF < 10,
OR
>30

Trying to use the MCR instruction is making things far more difficult than it needs to be. Use the input to increment the counter as you are doing. Only use the coil instruction for the lamp in a single rung. That rung will have two parallel branches. On branch will be the condition of the counter less than 10. The other branch will be the condition of the counter greater than 30.
Some older PLCs may not permit parallel comparison instructions. If yours is one of those, create individual rungs with each comparison instruction turning on a different internal coil instruction. Then add a third rung with contact instructions addressed to your two internal coils in parallel, turning on the lamp. That third rung is the OR instruction AustralIan referred to.

You could use the LIM instruction instead of the LES & GRT and do it all on one rung
and one output

What I will do is creat a new internal bit( for eg: B3:0/0) which activates b/w 10 to 30 and in another rung use XIO(B3:0/0) which turns light on

ya we cannot use same output which is being activated by two different things

Ken Moore said:

In the same rung (with branches as needed) you should have two conditions that energize the output.
IF < 10,
OR
>30

Click to expand...

Thanx a lot Ken, it worked.

https://ibb.co/s6sVkKq

Lim

I really appreciate the help from all of you guys. I will also try to learn about LIM instruction since I am not good at it.

Welcome to the forum!


What have you tried so far? Can you post a sample (PDF or text file or image or zip, etc.)?


I am certain you will want to assign a 1 or 0 (via OTE instruction, in A-B lingo) any single output only once; there is a way to effect a logical OR using "branches" on a single rung.

Both worked!
Thanks for the help guys again