Pneu 01 — Single cylinder

Briefing

A small pneumatic pusher: one double-acting cylinder driven by a 5/2 valve with two solenoids. EXTEND_SOL pushes the rod out, RETRACT_SOL pulls it back. If neither solenoid is on, or both are, the valve stays where it was and the rod holds still. Two reed switches report the ends of the stroke: RETRACT_LS is on when the rod is home, EXTEND_LS is on when it is fully out. They come from the cylinder, so they only change as the rod moves. Tap START once. The rod extends, and when it reaches EXTEND_LS it retracts by itself. When it is back on RETRACT_LS everything is off. START pressed while the rod is moving does nothing.

Objectives

• START extends the rod: EXTEND_SOL on, RETRACT_SOL off
• The extend command holds until the extended sensor closes
• At the extended sensor the rod turns round: EXTEND_SOL off, RETRACT_SOL on
• Back on the retracted sensor both solenoids are off
• START is ignored while the rod is moving

I/O Table

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

1. #1START → extend only

   The cycle starts by driving the rod out

2. #2Half a second later → still extending

   The extend command holds after START is released

3. #3Rod fully out → retract only

   The extended sensor ends the extend and starts the return

4. #4Rod home again → both solenoids off

   The retracted sensor ends the cycle

5. #5START while the rod is returning → nothing changes

   START only begins a cycle when the cylinder is at rest on the retracted sensor

6. #6START after a finished cycle → extends again

   A second cycle starts cleanly