Fresh Engineer

Hi, 

I want to create a ladder logic program that counts from 1 to 8. The number should only increase once complete a cycle. I want to get numbers 1 to 8 multiple with a fixed number inserted through HMI. After counting until 8, the value will reset back to 1.
Does anyone have any idea how to do this? 
As I know, we can use CTU to do this. But it will re-initialise the value every time download program.

You are correct about using the counter instruction.

Consider however that you could declare a tag of integer type (SINT, INT, DINT, USINT, UINT, UDINT) in a DB that has its retention attribute switched on. Then use the ADD instruction for increasing and MOVE instruction for the case where the counter tag reaches the count.

Watch out that the trigger for the ADD instruction will need to be edge triggered. Look for the instruction that helps with that.

Use the above hints and start a program block to do the job. Publish that here if you need more guidance. BUT you have to make an effort. Doing the work with the needed research is valuable a skill.

Assume You use S7-1200/1500 so you can use Inc (Increment)

if You use S7-300 change inc to Add with 1