User manual of EL8-EC***F AC Servo
40
2.11 Safe Torque Off (STO) Port
Port
Pin
Signal
Description
Remarks
1
2
7
8
1
24V
24v power supply
Connect to SF1 and SF2
when not in use. Do not use
to supply power.
2
0V
Reference ground
3
SF1
＋
Control signal 1
positive input
When SF1 = OFF or SF2 =
OFF,STO is enabled.
4
SF1
－
Control signal 1
negative input
5
SF2
＋
Control signal 2
positive input
6
SF2
－
Control signal 2
negative input
7
EDM
＋
External monitoring
device (EDM) with
differential double
ended output
When SF1 = OFF or SF2 =
OFF,EDM = ON
8
EDM
－
Introduction to Safe Torque Off (STO)
Function: Cut off motor current supply physically (through mechanical means)
STO module (CN6 connector) consists of 2 input channels. It cuts off the motor current
supply by blocking of PWM control signal from the power module. When the motor current
is cut off, the motor will still move under inertia and stops gradually.
The STO function is set up ready to be used by factory default. Please remove STO
connector if it is not needed.
STO functional principle
STO module cuts off the motor current supply and stops motor gradually by blocking of
PWM control signal from the power module through 2 isolated circuits. When a STO error
occurs, the actual status of STO can be determined by the EDM status feedback.
SF1 Input
Status
SF2 Input
Status
EDM Output
Status
PWM control
signal
Alarm code
ON
ON
OFF
Normal
-
ON
OFF
OFF
Blocked
Er 1c2
OFF
ON
OFF
Blocked
Er 1c1
OFF
OFF
ON
Blocked
Er 1c0
