Parker ac890 - Page 151

6-16 Safe Torque Off
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
Fault Operation
A fault is always detected when X11/01 and X11/03 are in opposite states for more than 3.0 seconds.
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.
3 One input is high and the other input is low. STO prevents the drive from starting. In this example, this
state persists for more than 3.0 seconds (being the maximum fault detection time), after which time the
STO logic transitions to state 4 without further changes in input state. The 890 has detected single-channel
operation.
Channel A: X11/01
Channel B: X11/03
Output: X11/05, X11/06
STATE
24V
0V
24V
0V
ON
OFF
3.0s
1 3 4