Based on contributions by Jesse.
Festo’s electronically controlled pneumatic valves can be switched directly by a Siemens PLC output, using Festo’s standard connecting cables. This is the quickest way to actuate a cylinder or valve from PLC logic without extra driver hardware.
What you need
- A Festo pneumatic valve with its Festo connecting cable.
- A Siemens PLC with a free 24V digital output, programmed in TIA Portal.
Steps
1. Wire the valve to the PLC
The connecting cable’s wires are color-coded:
| Color | Function |
|---|---|
| White | 24V (live) |
| Black | Signal |
| Blue | Ground |
Plug the wires into the PLC’s terminal. If your PLC’s signal output already supplies 24V when active, you don’t need to connect the white wire — the valve can switch from the 24V on the signal pin alone. Then plug the other end of the cable into the valve and tighten the holder ring.
2. Create an output tag
In TIA Portal, add an output tag in your default tag table matching the terminal you wired the signal wire into. This example also uses a start-button tag to trigger the program.
3. Switch the valve
Program the output in FBD (or your language of choice):
With just this, the valve stays switched only as long as the start button is held down.
4. Trigger the valve for a fixed duration
If you need the valve to stay on for a set time regardless of how long the button is pressed, use a TP (Time Pulse) block:
With a 1.5-second pulse: a quick press-and-release still triggers the full 1.5 seconds. Holding the button longer than 1.5 seconds only keeps the valve on for 1.5 seconds — you then need to release the button before you can trigger it again.
Common mistakes
- Wiring the valve directly to a plain output and expecting it to stay on after release — a direct output only stays high while the trigger condition is true; use a
TPblock if you need a timed pulse. - Forgetting to check whether your PLC output already supplies 24V — if it does, wiring the white (24V) wire as well is redundant.
Related
- How to connect a Siemens PLC to an Arduino over TCP or digital I/O — connecting a Siemens PLC to an Arduino over TCP or digital I/O
Rewritten and consolidated (Sept 2026) from the original student how-to’s: How to control Festo pneumatic switches using a Siemens PLC.