Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 343)

Section 6
Emergency STOP Design
6-7
On systems that support the controlled-stop feature, the velocity loop
remains enabled and the velocity command is reduced exponentially to
zero after an E-Stop occurs. This results in the velocity loop attempting to
bring the motor to a stop and/or hold it steady. After 2 seconds, the
controls software disables the velocity loop.
The control will also maintain the axis/drive enable signal to 1394 and
8520 digital servo amplifiers for this 2 second interval after E--Stop.
The commands sent to the drive (torque commands) are limited by the
torque limits defined for the axis in AMP (“MAXIMUM PERCENT
RATED TORQUE...”).
Important: If problems (such as amplifier faults) occur from overcurrent
conditions caused during a worst case E-Stop (E--Stop during rapid move),
you must reduce the AMP configured maximum percent rated torque
limits.
ATTENTION: We strongly recommend that the high-voltage
input to the amplifiers be disconnected by a contactor when the
E-Stop string opens. As a result of this power loss to the drive,
the only current available to the drive to bring the motor to a
stop and hold it is the residual bus energy stored in the drives.
The velocity loop from the control will attempt to stop and hold
the axes for 2 seconds after an E-Stop occurs. The amount of
time the drive system can actually pull current from the motor
to bring the axis to a stop and hold it in position varies
depending on machine factors (e.g., the size of the motor, the
speed at which it is traveling or its static load, and the amplifier
size)
Resetting E-Stop
Once the cause of the error has been corrected, press E-Stop reset.
the E-Stop string will reset and return system control to system
software.
depending on the value of the AMP parameter Control Reset on
E-Stop Reset, the control will either execute a control reset, which
returns the part program pointer to the top of the program, or leaves the
pointer at the block being executed when the E-Stop occurred.
END OF SECTION