
8. EMERGENCY STOP SIGNAL
B–63463EN/01
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Shutting off the servo amplifier power causes a dynamic brake to be
applied to the servo motor. Even when a dynamic brake is applied,
however, a servo motor attached to a vertical axis can move under the
force of gravity. To overcome this problem, use a servo motor with a
brake.
The FANUC servo amplifier α/β series products are designed to satisfy
the above requirements. The emergency stop signal should be input to the
power supply module (called the PSM) for α series. The PSM outputs
a motor power MCC control signal, which can be used to switch the power
applied to the power supply module on and off.
For the servo amplifier β series, input an emergency stop signal to the
servo amplifier, and control the turn–on/off of the motor power using an
external circuit.
The Digital Servo Adapter is designed to detect overtravel by using a
software limit function. Normally, no hardware limit switch is required
to detect overtravel. If the machine goes beyond a software limit because
of a servo feedback failure, however, it is necessary to provide a stroke
end limit switch, connected so that the emergency stop signal can be used
to stop the machine.
Fig. 8.3 shows an example showing how to use the emergency stop signal
with this Digital Servo Adapter and α series servo amplifier.
8.3
SERVO