Suppose we have a PLC connected to three pushbutton switches as shown in this illustration:
In the above diagram :
- X1 to X4 : Digital Inputs
- Y1 to Y4 : Digital Outputs
Determine the switch actuation statuses (i.e. pressed versus released) given the “live” display of the ladder logic program shown here:
Also, determine the status of the lamp connected to the PLC’s Y1 output.
Answer :
Switch statuses:
- Switch A = pressed
- Switch B = released
- Switch C = released
The lamp will be de-energized.
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A lampada só acenderar se A e C for prenssionados juntos
Translated : The lamp only glow if A and C together is present.
thank you
The lamp only glow without any action on pushbutton means exiting field wiring and logic instruction condition is true when power on
As per the ABC switch status,
Status A- NO Switch – In logic it is NC – Enabled state
Staus B – NC Switch – In Logic it is NO – Enabled State
Status C – NO switch – in logic it is NC – Enabled state
Therefore, Output(Y1) will glow until switch state change.