Closed Loop Halt

The Closed Loop Halt is one of the four types of RMC Halts. Use the Closed Loop Halt to halt the axis while remaining in closed loop control.

Tip:
The Halts do more than just stop the axis. If you simply wish to stop the motion in closed loop control, use the Stop (Closed Loop) (6) command instead. If you wish to stop the motion in open loop control, use the Stop (Open Loop) (22) or Open Loop Rate (10) commands.

When a Closed Loop Halt occurs, it takes the following steps:

The axis stays in closed loop and stops the axis at the rate specified by the Closed Loop Halt Deceleration axis parameter. If the axis is in Open Loop when this halt occurs, this halt will start an Open Loop Halt instead.
See the Stopping Details section below for details on how the stop behaves for various control modes.

Note:
It is the Target Velocity that is ramped down. If the Actual Position is lagging behind the Target Position, it will not stop until it reaches the Target Position. If you need the Actual Position to stop immediately, use an Open Loop Halt or Stop (Open Loop) (22) command instead.
Note:
The deceleration specified by the Closed Loop Halt Deceleration is the average deceleration. The instantaneous deceleration may exceed this value.
Note:
The Command Position is not affected by a Closed Loop Halt.

The Halted status bit is set and the axis is said to be in the halted state.
If the axis is part of a Halt Group, it starts a Closed Loop Halt on all axes in the group.

Pressure/Force Control

The Closed Loop Halt will keep the axis in pressure or force control, and will stop the target immediately.

Pressure/Force Limit

The Closed Loop Halt will keep the axis in pressure or force limit, and will not stop the target.

Stopping Details

This command ramps the current velocity or rate to zero in closed loop. The behavior of this command depends on the type of axis control:

Position PID
The velocity will ramp down from the current velocity to zero at the rate specified by the Closed Loop Halt Deceleration parameter, while remaining in position control.
Position I-PD
If the last motion command was Move Absolute (I-PD) (28) or Move Relative (I-PD) (29),the Target Position will stop immediately. Otherwise, the velocity will rampdown from the current velocity to zero at the rate specified by the Closed Loop Halt Deceleration parameter, while remaining in position control.
Velocity PID
The velocity will ramp down from the current velocity to zero at the rate specified by the Closed Loop Halt Deceleration parameter, while remaining in velocity control.
Velocity I-PD
If the last motion command was Move Velocity (I-PD) (38), the Target Velocity will stop immediately. Otherwise, the velocity will ramp down from the current velocity to zero at the rate specified by the Closed Loop Halt Deceleration parameter, while remaining in velocity control.
Open Loop
The axis transitions to closed-loop control and ramps the velocity to zero at the rate specified by the Closed Loop Halt Deceleration parameter in V/sec.
Pressure/Force Control
The Target Pressure Rate or Target Force Rate will be ramped to zero at the rate specified by the Closed Loop Halt Deceleration parameterin Pr/sec or Fr/sec.

Triggering a Closed Loop Halt

A Closed Loop Halt can be triggered in two ways:

By issuing the Closed Loop Halt (1) command.
Via Auto Stops.

After a Halt has Occurred

If the halt was caused by an Auto Stop, you should first make sure the error condition that caused it has been resolved before continuing. Once it has been fixed, you can clear the Halted status bit by issuing the Clear Faults (4) command. Issuing a valid motion command will also clear the Halted status bit.

Why Bother?

This halt is useful when you want to stop the axis but remain in closed loop control. If you have to stop the axis because it is vibrating, use the Open Loop Halt instead, since the axis will probably keep vibrating or oscillating as long as it is in closed loop control.

The Auto Stops can be set up to cause this halt when an error bit turns on.