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Programming PLC Applications
3.6.2
A rolling shutter gate
Task description
We want to implement a control system for a warehouse's rolling shutter gate that will enable
easy operation from both outside and inside. Safety facilities must also be integrated in the
system.
STOP
S0
b Operation
– It must be possible to open the gate from outside with the key-operated switch S1 and to
close it with pushbutton S5. Inside the hall it should be possible to open the gate with
pushbutton S2 and to close it with S4.
– An additional time switch must close the gate automatically if it is open for longer than
20 s.
– The states "gate in motion" and "gate in undefined position" must be indicated by a blin-
king warning lamp.
b Safety facilities
–
A stop button (S0) must be installed that can halt the motion of the gate immediately at any
time, stopping the gate in its current position. This Stop switch is not an Emergency OFF
function, however! The switch signal is only processed by the PLC and does not switch any
external power connections.
–
A photoelectric barrier (S7) must be installed to identify obstacles in the gateway. If it regis-
ters an obstacle while the gate is closing the gate must open automatically.
–
Two limit switches must be installed to stop the gate motor when the gate reaches the fully
open (S3) and fully closed (S6) positions.
3 – 28
S7
S2
S4
An Introduction to Programming
Warning lamp H1
S3
S1
S6
MITSUBISHI ELECTRIC
S5
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