
6-30
Safe Torque Off
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
To start the drive:
Ensure the Safety Demand switch is reset (contacts closed). Press the RESET button to ensure the Safety
Control Unit is reset; its contacts to the 890 should close making the STO function inactive, the 890 STO
output should then turn OFF. Then press the DRIVE START button.
To perform operational stop (non STO):
Press the DRIVE STOP button.
Wait for the motor to come to rest.
To invoke STO:
Operate the Safety Demand (contacts open). This should cause the Safety Control Unit to open its
instantaneous output, shown here as a single channel. This causes the drive to decelerate to rest using its
own software which is not safety critical in this instance. Note: the drive’s block diagram must be
configured to provide this ramp to rest functionality.
After a time delay set in the Safety Control Unit, the pair of delayed OFF output contacts open together.
This time delay must be set longer than the worst case time for the motor to come to rest.
In response, the drive will confirm, by energising KA1 via X11/05, that STO has been invoked. The user
may wish / require that this is verified by mechanisms not shown on this drawing.