ASDA A2-E
Chapter 7 Safety Function (Safe Torque Off, STO)
7-4
Revision April, 2015
(1) Status Description of STO Alarm:
See the figure below. When the motor runs properly (SERVO ON), if STO_A and
STO_B signal (which is also called safety signal) is lost for 10 ms at the same time,
AL500 occurs. Then, servo drive will be in Servo Off status.
STO_A
STO_B
S_ON
Servo
status
H
H
L
L
ON
OFF
Servo on
Servo off & AL500
10 ms
See the figure below. When the motor runs properly (SERVO ON), when one of the safety
signal is lost for 1 s, AL501 or AL502 will occur. Then, servo drive will be in SERVO OFF
status.
STO_A
STO_B
S_ON
Servo
status
H
H
L
ON
OFF
Servo on
Servo off & AL501
1 s
L
