Step sequence in ladder

Step by step

Pick a step. The rungs are drawn by the editor after Core scans the program up to that step.

Why it works

• Only one value of Step can be true at a time, so only one step's outputs are on.
• Each step has its own rungs: an EQU, what the step does, and a rung that moves Step on when its condition is met.
• Rungs run from the top down. A MOV that changes Step affects the rungs below it in the same scan, and the rungs above it on the next scan.

Ladder or SFC

• A short cycle with one path reads well in ladder.
• Use a Sequential Function Chart when steps branch, run in parallel or need timed actions. Each step then has a status tag and the chart shows where it is.

Common mistakes

• Latching outputs in a stepAn OTL stays on after the step ends. Use OTE under the EQU so the output turns off when the step changes.
• Two rungs moving Step in one scanIf two conditions are true together, the lower rung wins. Give each step one exit rung, or order them on purpose.

Instructions used

• Equal
• Normally open contact
• Move
• Output coil
• On-delay timer

Related

• SFC overview
• Equal