Door Lock Circuit - Mitsubishi Electric MELSEC-QS Series Safety Application Manual

5
SAFETY APPLICATION CONFIGURATION EXAMPLE (USING A
SINGLE SAFETY PROGRAMMABLE CONTROLLER)
5.6.5

Door lock circuit

(1) Application overview
This application prevents the door from being opened until a robot is de-energized
with the safety switch on the door of a safety barrier.
The safety switch is usually interlocked with spring. By applying a voltage to a
solenoid, the interlock is released and the door can be opened.
The robot cannot be started while the interlock is released or the door is open.
This section shows an example where the interlock of the safety switch is released by
activating the stop switch and the safety switch is re-interlocked by activating the reset
switch.
Start and stop of the robot is controlled with contactors that close and open the power
supply.
Connect the safety switch and contactors to a safety programmable controller.
The safety programmable controller turns on/off the main contacts of the contactors
with sequence program.
When the safety programmable controller detects an error by self-diagnostics, outputs
to the contactors turn off independent of the sequence program.
In this case, the outputs remain off until the safety CPU module or CC-Link Safety
remote I/O module is reset independent of the sequence program.
Configure the sequence program so that the following functions can be achieved.
1) After ensuring safety (The safety switch is on.), activating the reset switch
and then the start switch turns on the contactors.
2) When the main contacts of the contactors are welded, do not start the
robot. Input the auxiliary contacts (normally closed contacts) to the safety
programmable controller to check for welding.
3) The reset switch and start switch become valid only when turned off to
avoid operation at contact welding or short-circuit.
4) Activating the stop switch turns off outputs to the contactors.
After that, release the interlock to the safety switch (The safety barrier door
can be opened).
5) Activating the reset switch re-interlocks the safety switch.
6) When an error is detected in the safety remote I/O station on CC-Link
Safety after operation, outputs to the contactors turn off.
5.6 Case Examples
5.6.5 Door lock circuit
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