
6-14
Safe Torque Off
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
STO Input Timing Diagrams
Ideal Operation
In ideal operation, both inputs X11/01 and X11/03 should change state simultaneously reflecting true dual-
channel operation as intended.
States:
1
Both inputs are low. STO prevents the drive from starting. User output is ON. This is the “safe torque off”
state of the drive.
2
Both inputs are high. Drive is able to run under software control. User output is OFF.
Channel A: X11/01
Channel B: X11/03
Output: X11/05, X11/06
STATE
24V
0V
24V
0V
ON
OFF
1
2
1