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Thursday, August 21, 2025

Programmable Logic Controller - Up Down Counter in PLC

Another key aspect in the PLC programming is the concept of the up down counter. This post covers the basics of it.


Setting up a Counter

Setting up a counter

The above procedure calls a Up-Down counter C002 with a present value for 10 counts

Counting cement bags

A motor driven conveyor belt carries cement bags. Every time a start push button is pressed, run the conveyor to deliver 10 cement bags at the other end. Glow a green light when the conveyor is running and glow a red light when the conveyor is not running.

Input – Output Allocation - Counting Cement Bags


<Relay>
<No.> <Label> <Comment1> <Comment2> <Comment3>
0000 :START Start Push Button
0001 :STOP Stop Push Button
0002 :SENSOR Sensor Output
0003 :DUMMY Dummy
0500 :CONVEYOR Conveyor Motor
0501 :GREEN Green Light
0502 :RED Red Light
<Counter>
<No.> <Label> <Comment1> <Comment2> <Comment3>
C000 :COUNTER Counting till 10

Ladder Logic Program - Counting 10 Cement Bags

Ladder Program - Count 10 bags

Lets Combine Timer and a Counter

A motor driven conveyor belt carries cement bags. If a start push button is pressed, run the conveyor to deliver 10 cement bags at the other end continuously with an interval of 3 sec. Glow a green light when the conveyor is running and glow a red light when the conveyor is not running. Provide an emergency stop push button to stop the operation any time.

Input – Output Allocation - Timer and Counter


<Relay>
<No.> <Label> <Comment1> <Comment2> <Comment3>
0000 :START Start Push Button
0001 :STOP Stop Push Button
0002 :SENSOR Sensor Input
0003 :DUMMY Dummy Input
0500 :CONVEYOR Motor for Conveyor
0501 :GREEN Green Light
0502 :RED Red Light
0503 :TEMPO Temporary Output
<Timer>
<No.> <Label> <Comment1> <Comment2> <Comment3>
T000 :TIMER1 Timer for 3 sec
<Counter>
<No.> <Label> <Comment1> <Comment2> <Comment3>
C200 :COUNTER1 Counter for 10 bags

Ladder Logic Program - Counter and a Timer

Ladder Program - Counter and a Timer

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