3.4.8
The STO (Safe Torque Off) function can be utilized to bring the drive to a torque-free, safe condition via
two independent inputs. The drive output power stage is switched off if either one of the inputs is not
powered.
For in-depth details on the STO functionality separate document «EPOS4 Application Notes».
Activation of power stage
In order to activate the power stage, both STO inputs must be powered.
Module
Header Pin
Table 3-50
Circuit type
Input voltage
Max. input voltage
Logic 0
Logic 1
Input current at logic 1
Reaction time
Figure 3-43
maxon motor control
EPOS4 Positioning Controller
EPOS4 Module/Compact 24/1.5 Hardware Reference
Safe Torque Off I/Os
Compact/CB
Connector
Pin
–
X9 | 8
B15
–
B16
X9 | 7
B17
X9 | 1
B18
X9 | 2
B19
X9 | 3
B20
X9 | 4
B21
X9 | 5
B22
X9 | 6
STO I/Os – Pin assignment
STO-IN1 circuit (analogously valid for STO-IN2)
Document ID: rel6627
Edition: November 2016
© 2016 maxon motor. Subject to change without prior notice.
Signal
Activation voltage for STO inputs (+5 VDC)
V
Note: Do not use this voltage for any other
STO
purpose
V
Auxiliary output voltage (+5 VDC; I
Aux
GND
Ground
STO-IN1+
Safe Torque Off input 1, positive signal
STO-IN1−
Safe Torque Off input 1, negative signal
STO-IN2+
Safe Torque Off input 2, positive signal
STO-IN2−
Safe Torque Off input 2, negative signal
STO-OUT+
Safe Torque Off output, positive signal
STO-OUT−
Safe Torque Off output, negative signal
Safe Torque Off inputs 1...2
Optically isolated input
0...+30 VDC
±30 VDC
<1.0 VDC
>4.5 VDC
>2 mA @ 5 VDC
typically 3.2 mA @ 24 VDC
<25 ms
Setup
Connection Specifications
Description
≤150 mA)
L
3-61
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