Basic HTML Version
21
A plausibility check reveals
faults with different causes
• Solenoid coils, final control
element or pushbutton
generate a signal
• Energy switching element,
a valve in this case
Change of status
• From 0 to 1 or
• From 1 to 0
Sensors
E.g. piston position sensing,
pressure sensor, proximity
sensor, displacement encoder or
flow meter must register the
change of switching status
Pneumatic diagnostic options
Plausibility check
The PLC checks whether a signal change has taken place within a
specific period t, and if the desired change in status has occurred.
Plausibility
check t
Proximity sensor (S1, S2)
Output signal
PLC
Displacement encoders
Pressure
sensors
Flow meter
Switching position sensing
Status
Time t
Signal (solenoid coil, final control
element, pushbutton, etc.)
Sensor
(piston position sensing, pressure
sensor, proximity sensor, flow
meter, roller lever)