Rockwell Automation Publication MOTION-RM003I-EN-P - February 2018 423
selection is only valid if the connected controller is supplying the "Run/Idle" Real
Time header.
Safe Stopping Action
Usage Access T Data
Type
Default Min Max Semantics of Values
Optional - D
Safety Only
Set/
SSV#
USINT 0 - - Enumeration:
0 = Current Decel
1 = Ramped Decel
2-127 = (reserved)
128-255 = (vendor specific)
# Indicates the attribute cannot be set while the tracking command (Tracking Command bit in CIP Axis Status is true).
When an SS1 or SS2 Active condition occurs, as indicated by the Axis Safety
Status attribute, and the Axis Safety Stopping Source is set to Connected Drive,
this value determines the stopping method the drive is to apply to the motor. The
selected stopping method is applied while in the Stopping state and the final state
after the stopping method completes is the Stopped state. In this final state the
device's inverter power structure will either be Disabled and free of torque, if
initiated by an SS1 Active status bit, or actively held (Hold selection) in a static
condition if initiated by an SS2 Active status bit.
Safe Stopping Action Bit Descriptions
Bit Required/Opt
ional
Name Description
0
R/C
O/F
Current Decel
Current Decel leaves the power structure and any active
control loops enabled while stopping. If configured for
position control mode, the drive forces the position
reference to hold its current value until the axis reaches
zero speed. Once at zero speed the position reference is
immediately set equal to the actual position to hold the
axis at standstill. If in velocity control mode, the drive forces
the velocity reference to zero. In either case, forcing the
position or velocity reference signals to a fixed value results
in a rapid increase in control loop error of the moving axis
that saturates the output current of the drive to the
configured Stopping Torque that brings the motor to a stop.
In torque control mode, the drive directly applies the
configured Stopping Torque to the torque command signal
to decelerate the motor. When the velocity feedback value
reaches zero speed, the torque command is set to zero. In
frequency control mode the Current Vector Limit attribute,
rather than the Stopping Torque attribute, is used to
regulate the stopping current. Once stopped, or the
configured Stopping Time, or factory limit expires, the
Current Decel stopping action is complete.
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