
Safe Torque Off
6-13
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
Truth Table
Overview
STO
Input A
X11/01
STO
Input B
X11/03
Drive Function
STO
Status
Output
X11/05,
X11/06
STO Active
0V
0V
Drive cannot start or supply power to its motor. STO trip
reported if drive is running or drive started is attempted.
This is the intended safe state of the product with correct
dual-channel operation.
ON
Abnormal one-
channel
operation
detection
24V
0V
Drive cannot start or supply power to its motor. STO trip
reported if drive is running or drive start is attempted. If either
of these conditions persists for more than 3.0 seconds (the
maximum fault detection time), the STO function will lock
into a fault state. The drive cannot start until the fault is
rectified, all power is removed and reapplied (both mains and
any auxiliary 24V dc power)..
This is single channel operation and thus deemed not as
intended for category 3 / PLe / SIL3 structure
implementation.
OFF
0V
24V
STO Inactive
24V
24V
Drive is enabled to run under software control. The drive can
supply power to its motor.
OFF