Festo VTSA Series Description page 132

4. Commissioning
LED Switching position of the
valve
Out Normal position
Lights up Switching position
yellow or
Normal position
Tab. 4/6: Meaning of the LED display (VTSA... valve terminal with multi−pin node)
4−14
Valve terminal with multi−pin node
The LEDs indicate the switching status of the valve solenoid
coils.
Meaning
logical 0 (signal not applied)
logical 1 (signal is present)
logical 1 but:
The operating voltage of the valves lies outside the
permitted tolerance range (21.6 V to 26.4 V DC or
99 V to 121 V AC)
Compressed air supply not OK
or
Pilot exhaust air blocked
or
Servicing required
Festo P.BE−VTSA−44−EN en 0905e