354
6 FUNCTIONAL SAFETY
6.4 Safety sub-function
STO function
Outline
This function electrically shuts off the servo motor driving energy with input signals from external devices (shut-off by the
secondary-side output). This is equivalent to the stop category 0 of IEC/EN 60204-1. The function is also used for an
emergency stop when an internal diagnosis error is detected. Use the function while the servo motor is stopped.
Operation sequence
■
STOC (STO command)
After servo-off, turn off STOC (STO command) while the servo motor is stopped. Turning off STOC (STO command) will
activate the STO function. While STO is activated, the energy supply to the servo motor is shut off and the dynamic brake is
activated. The servo motor returns to normal operation by turning STOC (STO command) back on.
ON
ON
OFF
0 r/min
(mm/s)
ON
OFF
Servo motor speed
SON (servo-on)
or
servo-on command
STOC (STO command)
ON (disabled)
OFF (enabled)
WNG (warning)
ON (enabled)
OFF (disabled)
Base circuit
(energy supply to
servo motor)
STOS (STO output)
OFF (shut-off)
STO state
Normal operation
Normal operation