Counters in PLC Programming with Example

[vignesh]

Discuss the working of counters in ladder logics with PLC programming examples.

A process where a timed interval is started when a count reaches a preset value.

Time a Process after a Count has been Reached

After a count of 5 from a sensor, a paint spray is to run for 25 seconds.

Counters in PLC Programming

Counters in PLC Theory

Down Counter (CTD) in Ladder Logic

The Down Counter (CTD) is an instruction that counts false-to-true rung transitions in ladder logics. Down Counter (CTD) Rung transitions can be caused by events occurring in the program such as parts traveling past a detector or actuating a limit switch. When rung conditions for a CTD instruction have made a false-to-true transition, the accumulated value is decremented by one count, provided that the rung containing the CTD instruction is evaluated between these transitions. The accumulate…