Counter

The Counter instruction counts up, down, or both in response to OFF-to-ON transitions of enabling rungs. It stores the current count in a register and turns on a completion bit when the count reaches the set point. A reset rung clears the completion bit.

Source checked17/17 values · 2026-10-26

Specification

1 source

Language	ladder
Code	Counter
Group	Counter

Parameters

Name	Data type	Description
Counter Number	CT memory type	Assigns the counter number.
Set Point	Integer constant or DS/DD address	Target count value.
Count Type	selection	Count Up, Count Down, or Count Up & Down.
Current Value	Counter Data register	Holds the current count; automatically assigned from the counter number.
Completion Bit	CT bit	Turns ON when current value reaches the set point; same as counter number.

Study notes

The counter number must be a CT memory type.
Set Point can be an integer constant or a DS/DD data memory address.
Count Type options are Count Up, Count Down, and Count Up & Down.
Current Value is automatically assigned to the corresponding Counter Data register: CT1 corresponds to CTD1, CT2 to CTD2, etc.
The Completion Bit is the same as the Counter Number.
Count Up & Down uses two enabling rungs, one for up counts and one for down counts.
The completion bit turns ON when the current value reaches the set point and turns OFF when the reset rung is enabled.