Pneumatic Circuit Builder

You build a pneumatic circuit from standard symbols, pipe the ports together and press Run. Cylinders move, valves switch and pressurised lines light up. A check tests the piping rules and then operates the circuit by itself. The sheet exports as a PDF with the drawing, a parts list, cylinder forces and air use, and the displacement-step diagram.

It is a logic model. Valves switch instantly and pipes have no volume, so it checks the sequence and the signal logic, not timing, load or safety. A safety-related circuit needs validation to ISO 13849 and a test on the machine.

Who it is for: freshers learning how valves and cylinders work together, and the design team that wants a quick circuit with a parts list and cylinder data.

1. Choose Single-acting cylinder, push-button in Load an example, or press the button below.
2. Press ▶ Run in the pinned controls at the top right.
3. Click the push-button valve S1 on the sheet and hold the mouse down. The cylinder A extends. Let go and it retracts on its spring.
4. Look at the line colours: gold lines carry supply air, bluish-grey lines are vented, dashed lines are pilot signals.
5. Press ✎ Edit and then Check circuit under section 03.

The check reports 0 errors, 0 warnings and the automatic run shows: press S1 briefly: A+ A− (out and back) and press and hold: A+ (stays extended while held). The one NOTE says the cylinder has no flow control, so its speed is not adjustable.

Load this example

Pinned simulation controls (top right). Run, Pause, Step (to the next movement), Reset (to the start position) and Edit, a speed choice from 0.25× to 4×, a mode label and the simulated time.

User manual button. Next to Full screen in the toolbar. It opens this manual in a panel on the right, also in full screen, so you can read it and load its examples while you work. Close or Esc shuts it.

Sheet toolbar. Load an example, Undo, Redo, Rotate, Delete, Clear, Save .fpc file, Open file, Full screen and Light sheet (colours for printing and screenshots).

Palette. Cylinders, valves, flow controls, logic elements, air service unit, silencers, sensors and the electrical parts. Expand all and Collapse all open or close the groups.

BOM drawer. The BOM tab beside the sheet opens the parts list as you draw, with a CSV download.

Under the sheet. Settings of the selected symbol, then the cylinder positions, the event log and the displacement-step diagram.

Drag a symbol from the palette onto the sheet, or tap it to place it. A part-bearing symbol (cylinder, valve, flow control, air service unit, silencer, position sensor) opens a pop-up on drop:

• A cylinder is sized from the force you need.
• The others are filtered by flow or thread.
• Choose the brand and the part number. You can mix brands freely.

A green dot on a symbol means it is defined. Press Define later to skip the pop-up; double-click the symbol, or press Define in its settings, when you are ready. Click a symbol to change its settings. R rotates the selected symbol and Delete removes it.

Drag from the small circle at the end of a connection stub to the circle on another port. Each wire joins ports into one air line.

• Unconnected exhaust ports (3 and 5) vent to atmosphere by themselves.
• Every other port should be connected; the check reports ports left open.
• Electrical ports are drawn in blue and connect only to other electrical ports.

A valve is drawn as one box per position. The connection stubs sit on the right-hand box, the rest position when the spring is on the right. The actuator on the left acts on the left box, so a push-button on the left of a spring-return valve switches to the left box while it is pressed. While the simulation runs, the box in use is shaded.

• 3/2 valve: 1 supply, 2 output, 3 exhaust.
• 5/2 valve: 1 supply, 2 and 4 outputs, 3 and 5 exhausts.
• Pilot 14 joins 1 to 4. Pilot 12 joins 1 to 2.
• A roller valve is labelled by what it senses: a0 is cylinder A at its retracted end, a1 at its extended end.

Symbols follow ISO 1219; port numbers follow ISO 5599.

Press Run, then operate the circuit with the mouse. Click a push-button valve or an electrical push-button on the sheet to press it. Hold the mouse down to hold it; a lever latches on each click. Editing the sheet stops the simulation.

How the simulator decides

• From the supply, air spreads through the open path of each valve at its current position, through flow controls and through check valves in their free direction.
• From atmosphere, venting spreads backwards the same way.
• A line reached by supply is pressurised, by atmosphere vented, by neither it keeps its last state (trapped air).
• A line reached by both is a leak of supply to atmosphere, reported as a short circuit.
• A cylinder moves when one chamber is pressurised and the other can vent. If the other chamber has no exhaust path it is blocked.
• Valves are re-evaluated until the circuit settles; a circuit that never settles is reported.

Speed, sensors and memory

• Cylinder speed is the unthrottled speed you enter, reduced by any one-way flow control wired directly to a cylinder port. Meter-out throttles the air leaving; meter-in the air entering.
• A roller valve operates when its cylinder is within 1.5 percent of the chosen end.
• A valve with air pilots on both sides and no spring is a memory valve. It holds its last position until the opposite pilot is pressurised. If both pilots are pressurised at once the tool reports signal overlap.

A 24 V supply feeds the electrical part. A solenoid is energised when its terminal is joined to 24 V through closed contacts: contacts in series act as AND and contacts in parallel as OR. The coil return is the common 0 V and is not drawn.

• Limit switch (mechanical roller), inductive proximity sensor (senses the rod or a target) and reed sensor (reads the magnet on a magnetic-piston cylinder) all act as a contact operated when the cylinder is at the chosen end. They differ in symbol and parts list.
• Push-button: momentary or latching; a second contact can be coupled to it.
• Relay: drop a coil, then drop contacts and choose that coil in their settings. A contact is normally open or normally closed and follows its coil.
• Self-holding (latching): a relay contact in parallel with START, wired back into the same coil. If the OFF button sits in series with the whole circuit, OFF dominates; if only in the holding branch, ON dominates.
• Pressure switch: a pneumatic port and an electrical contact. In the simulator it closes when its line carries pressure and the piston has reached the end stop, which is how pressure-dependent reversal works.
• Lamps and buzzers light when their terminal is live.
• A valve with a solenoid on both sides and no spring is a memory valve; the check reports it if both solenoids are energised together.

Press Check circuit in section 03. It tests the wiring rules (every port connected, every cylinder chamber reachable by supply and by exhaust, pilots and rollers assigned) and then runs the circuit by itself.

What the automatic run does

For each push-button or lever valve it runs the circuit from the start position with that valve pressed briefly, and again held. It records every cylinder movement as A+ (extend) or A− (retract), detects a repeating cycle, and stops when nothing has moved for 1.5 s. A circuit that cycles after a short press is flagged. The displacement-step diagram in the PDF comes from this run.

Where two buttons are needed (AND circuits) the run also tries them together. Click a message line to select the symbol it refers to. NOTE lines are information.

Click a cylinder on the sheet to size it from the force you need and choose its brand, series and part number. Fittings, tubing, valves, flow controls and the air service unit then fill into the parts list. Choose a brand for the parts list and everything follows it unless you set a brand on an item.

Cylinder data

The table gives bore and rod, stroke, force out, force in and air per cycle at the lowest of the supply and air-service-unit pressures. Forces are theoretical (pressure × area, no friction); expect 80 to 90 percent at the rod. Air per cycle is free-air litres for one extend and one retract, without pipe volume.

Hand check: Ø32 / 12 mm, 150 mm stroke at 6.0 bar

• Piston area = π/4 × 32² = 804.2 mm². Force out = 6 × 804.2 / 10 = 483 N.
• Annulus area = 804.2 − π/4 × 12² (113.1) = 691.1 mm². Force in = 415 N.
• Swept volume = (804.2 + 691.1) × 150 = 0.2243 L. Times (6 + 1.013) / 1.013 = 6.92 gives 1.55 NL per cycle.

These are the figures the tool shows for the Festo 1 example below.

PDF

Fill Title, optionally Prepared by and Drawing number and press Download PDF: circuit on sheet 1 with a title block, then parts list, cylinder forces and air use, the simulated sequence with its displacement-step diagram, and the check results.

Part numbers marked listed match a code seen in a catalogue listing; type code follows the maker’s code structure; series only names the series. Always confirm every number, option code and coil voltage in the maker’s current catalogue before ordering. Tubing counts only the lines between valve and cylinder; add supply and pilot lines.

Load this example

Each example was run through the check; the results quoted are what the tool reports. After loading, press Run and try them.

A. Single-acting cylinder, push-button

One cylinder A operated from push-button valve S1. Result: passes. Short press: A+ A−. Held: A+. Load this example

B. Double-acting cylinder with speed control

A double-acting cylinder A, push-button valve S1 and two one-way flow controls FC1 and FC2 wired to the cylinder ports. Result: passes with OK on the rules. Short press: A+ A−; held: A+. The cylinder is Ø32/12 with 200 mm stroke: 483 N out, 415 N in, 2.07 NL per cycle. Change a control to meter-in or meter-out and watch the speed change. Load this example

C. Sequence A+ B+ A− B− with limit valves

Two cylinders A and B, memory valves V1 and V2, roller valves a0, a1, b0, b1, and an AND element for the start. Result: passes. A short press runs A+ B+ A− B− once and finishes at 2.5 s with both retracted. Pressed and held it repeats about every 2.5 s. Load this example

D. Electro-pneumatic A+ B+ A− B− with reed sensors

The same sequence with solenoid valves V1 and V2, reed sensors a0, a1, b0, b1 and a start button SB1. Result: passes. Same sequence, 2.5 s, and the same repeat when SB1 is held. Load this example

E. AND: assembly station (Festo 5)

The cylinder moves only when S1 and S2 are pressed. Result: passes. Pressing S1 alone, or S2 alone, gives no movement from this input alone; pressing both together gives 1A+ 1A−. Load this example

F. OR: flap control (Festo 7)

Either S1 or S2 moves the cylinder. Result: passes. S1 alone gives 1A+ 1A−, S2 alone gives 1A+ 1A−, both together the same. Load this example

G. Latching, switch-off dominant and switch-on dominant (Festo 15 and 16)

A relay K1 with a self-holding contact, a start button S1 and a stop button S2. Result: both pass. A short press of S1 makes 1A+ and the cylinder stays extended, because the relay holds itself on. Run them, press the other button and compare which signal wins when both are pressed. Load Festo 15 Load Festo 16

H. Pressure-dependent reversal (Festo 18)

A pressure switch 1B closes when the line carries pressure and the piston has reached its end stop, and that reverses the cylinder. Result: passes. S1 and S2 together give 1A+ 1A−. Load this example

I. Two cylinders, magazine switch and buzzer (Festo 20)

S1 is a latching switch. With S1 on, a press of S2 runs 1A+ 2A+ 1A− 2A−, finishing at 1.7 s; held, it repeats about every 1.7 s. Load this example

The twenty circuits under Electropneumatics workbook follow the exercises and solutions of the Festo Didactic workbook Electropneumatics, Basic Level TP201. They are redrawn in this tool’s own symbols and ladder layout and are teaching circuits, not machine designs.

• Cylinder will not move. One chamber must have supply and the other an exhaust path. If the check says “blocked”, an exhaust port is not vented or a line is closed.
• Short circuit reported. A line is reached by both supply and atmosphere, for example a valve passing supply straight to an open exhaust.
• Signal overlap. Both pilots of a memory valve are on at once. The signal that set the valve is still present when the opposite signal arrives. Remove or cancel the first signal before the second is needed.
• Port not connected. Pipes must end on the small circle of a port. Click the message to find the symbol.
• Roller or pilot not assigned. Select the valve and choose which cylinder end it senses.
• Cycles after a short press. The check flags a circuit that repeats after a short start press, because most machines should do one cycle per start. Look at what restarts the sequence.
• Solenoid never energises. Check it is joined to 24 V through closed contacts, and that a relay contact points at the right coil.
• Speed will not change. The flow control must be wired directly to the cylinder port. Exhaust flow controls on the valve exhaust ports are not modelled.

Save .fpc file downloads the circuit and Open file loads it again. Keep your own copies of any work. Loading an example (list or manual button) replaces the drawing, so it asks first.

Timers and time-delay relays, counters and PLC logic, relay contact bounce, sensor response time and switching hysteresis, valve switching time, pipe volume and pressure drop, cylinder cushioning and load, time-delay valves, pressure-sequence valves, vacuum and proportional valves. The part series in the parts list are typical examples only. Always confirm sizes and part numbers in the supplier’s current catalogue.

• v17 · 10 Oct 2026
  Added the page background image and this user manual, which also opens from a User manual button next to Full screen with nine worked examples that load onto the sheet. The manual is updated with every change to the tool.
• v1 to v16
  Earlier builds: symbol palette with brand and part-number pop-ups, simulation with flow controls and memory valves, electro-pneumatic parts and relays, twenty Festo TP201 workbook circuits, automatic check, displacement-step diagram, parts list and PDF.