Safe stop types, Safe torque off with standstill checking – Rockwell Automation 21G PowerFlex 750-Series AC Drives Reference Manual User Manual
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Rockwell Automation Publication 750-RM001F-EN-P - February 2012
Chapter 6
Safe Stop and Safe Stop with Door Monitoring Modes
Safe Stop Types
Use the P45 [Safe Stop Type] parameter to configure the type of stop that the
system executes when a Safe Stop is initiated. A Safe Stop can be initiated by a
transition of the SS_In input from ON to OFF or by the occurrence of a Stop
Category fault.
While the safety option executes the configured Safe Stop Type, it continues to
monitor the system. If a Stop Category fault is detected, the safety option sets the
outputs to a faulted state, but allows for the door control logic to be set to Unlock
if the feedback signals indicate Standstill Speed has been reached.
Safe Torque Off with Standstill Checking
This Safe Stop Type lets you access the hazard area immediately after motion is
detected as stopped rather than waiting until a specific time has elapsed.
When Safe Torque Off with Standstill Checking is initiated, motion power is
removed immediately and the configured Stop Delay P47 [Max Stop Time]
begins. If the configured Standstill Speed is detected any time after the Safe Stop
has been initiated and before the end of the configured Stop Delay, door control
logic is set to Unlock.
If the Standstill Speed is not detected by the end of the configured Stop Delay, a
Stop Speed fault occurs and the door control logic remains set to Lock until
Standstill Speed is detected.
Figure 11 - Timing Diagram for Safe Torque-off with Standstill Checking
(1) This signal is internal, between the safety option and drive.
(2) DC_Out output shown configured as Power to Release. See
for more information.
Stop Request
Stop Delay: P47
Safe Torque-off
Active
Door Control
Output Unlock
P48 [Standstill Speed]
SS_Out Output
Motion Power
(1)
Speed
Time
SS_In Input
DC_Out Output
(2)
Stop Command
(1)