Write a plc program where there are boxes running by start-stop pushbuttons (PB) and there is a photocell sensor to count the number of boxes and there is a set pushbutton (PB) whenever it’s pressed the counter start counting from a preset value.
Note the best practice to learn the PLC programming is to start writing the PLC program, take your time before you review the answer.
 Inputs & outputs:
I0.0: Start Push Button (Normally Open contact)
I0.1: Stop Push Button (Normally Closed Contact)
I0.1: Set Push Button (Normally Open Contact)
Q0.0: conveyor
C1: Counter
Start the Counting from a Preset Value in PLC
PLC Logic Explanation
Network 01
When the Start PB has pressed the set coil of the SR flip flop is energized and the conveyor will run.
If the stop PB is pressed the reset coil of the SR flip flop is energized and the conveyor will stop.
Network 02
When the carton box passes by the photocell the count up coil of the counter C01 is energized and 1 count to the counter’s counts.
When the set PB has pressed the count value in the preset value PV will be moved to the counter’s counts.
When the stop PB is pressed the counter’s counts will be reset to 0.
Author: Karim Ali Anwar