PLC circuits
Four-Piston Sequence with a PLC
What is a four-cylinder sequence with a PLC?
It is a PLC application in which four pneumatic cylinders run in a set order for set times. Each cylinder is controlled by a spring-return 5/2 valve: when the valve coil is energized the cylinder extends, when it is de-energized it retracts.
Where is it used?
It is used on assembly machines, press and moulding machines, packaging and labelling machines and automatic test rigs. Electro-pneumatic systems are the most common drive type in industrial automation.
PLC wiring and ladder program
The valve coils go to PLC outputs, the start-stop buttons to inputs. In the program, timers start each other in turn to run the cylinders. This application clearly shows how the timer chain grows as the number of steps increases.
What to watch out for
In real systems, using cylinder position sensors (magnetic cylinder switches) instead of times is safer; the next step does not start even if a cylinder is late.
Parts used
- PLC
- PLC1
- Solenoid valve
- Y1, Y2, Y3, Y4
Run it in the simulator.
This circuit is ready in the CoilPath library. Open it, press the buttons and follow the current. It also comes with a wiring view and a panel layout.