Mitsubishi Electric MELSEC iQ-R Series Safety Manual page 138

Two-hand operation switch
■Safety application overview
This application prevents a worker from approaching to hazardous area by energizing a robot only when two buttons are
simultaneously pressed with both hands.
A press machine that starts sliding by pressing two buttons is the typical application example. Start and stop of a robot is
controlled by turning on or off the main contact of the contractor which opens and closes the power source of a robot.
Connect the two-hand operation switch and electromagnetic contactors to a safety programmable controller.
The Safety CPU controls on or off of the electromagnetic contactors with program.
When the safety programmable controller detects an error with the self-diagnostics, outputs to the electromagnetic contactors
turn off independent of the program.
In this case, regardless of the program, the outputs remain off until the Safety CPU or safety remote I/O module is reset.
Configure the program so that the following functions can be achieved.
1.
After ensuring safety, press the two buttons on the two-hand operation switch. The electromagnetic contactors turn on
only when timing when the buttons are pressed is within 500ms difference.
2.
When a safety electromagnetic contactor is welded, input the electromagnetic contactor (normally closed contact) to the
safety programmable controller to prevent starting, and check for welding.
3.
When one or both of the hands are released from the buttons or an error is detected in the safety remote I/O module after
operation starts, outputs to the electromagnetic contactors turn off.
(Partially quoted from "Safety Guide Book - the safety measures of machinery in the workplace": Nippon Electric Control
Equipment Industries Association)
5 SAFETY APPLICATION CONFIGURATION EXAMPLES
136
5.1 System Configured by a Safety CPU