Safe Torque Off
6-15
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
Normal Operation
In normal operation, there can be a small time difference between changes of state on X11/01 and X11/03, due to
different delays in the operation of two sets of relay contacts.
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.
3
One input is high and the other input is low. Drive cannot start due to STO. User output is OFF. Normal
operation allows this state to persist for up to 1.6 seconds which is the minimum fault detection time
required to generate a fault (3.0 seconds is the maximum). These tolerable time differences are normally
caused by switches or relays; they should be kept as short as possible.
Channel A: X11/01
Channel B: X11/03
Output: X11/05, X11/06
STATE
24V
0V
24V
0V
ON
OFF
1
2
1
3
< 1.6s
3
< 1.6s