Delta RMC151 - Manual (Page 172)

RMC70/150 and RMCTools User Manual
Pressure/force limit is a special type of pressure or force control. With pressure or force
limit, the pressure or force is limited during the position or velocity motion of an axis.
Pressure/force limit cannot be used simultaneously with pressure/force control. If the axis
is in pressure/force limit, and a command is issued that puts the axis in pressure/force
control, the pressure/force limit will no longer be active and the axis will start controlling
the pressure or force. However, the Pressure/Force Limit Enabled status bit will still be
set, and if the axis exits pressure/force control, it will resume pressure/force limit.
Determining Whether Pressure/Force Limit is Required
• If you want to transition between position and pressure or force control, and each
control mode does not depend on the other, then you probably do not need pressure
or force control.
• If you want to transition between position and pressure or force control, but you want
to make sure the axis will not exceed a certain position while controlling
pressure/force, you probably need pressure/force limit. However, you can use
pressure/force control and monitor the other values from a user program to handle
error conditions.
• If you want to perform position or velocity motion, but limit the pressure or force
during the motion, then you probably need pressure or force limit.
If you will be using pressure/force limit, see the Pressure/Force Limit topic. If you will be
using pressure/force control, continue reading this topic.
Enter Pressure or Force Control
To enter pressure or force control, issue one of the following commands. Notice that
these commands will enter pressure/force control, not pressure/force limit.
• Hold Current Pressure/Force (19)
This command will enter pressure or force control and hold the current pressure or
force. This command is a good choice if your axis is stopped or moving slowly.
• Enter Pressure/Force Control (Time) (45)
This command will enter pressure or force control and then ramp to the requested
pressure or force within the specified time.
• Enter Pressure/Force Control (Auto) (44)
This command will enter pressure or force control and ramp to the requested pressure
or force. The ramp is automatically calculated based on the current rate of change of
the Actual Pressure or Force. This command is designed to be used when the system is
moving and the Actual Pressure or Force is rising quickly, which indicates the axis is
encountering the resisting pressure or force. This command can provide a very smooth
transition from position to pressure control while the system is moving.
• Enter Pressure/Force Control (Rate) (46)
This command will enter pressure/force control and then ramp to the requested
pressure/force at the requested rate and acceleration.
When the axis is in pressure or force control, the Pressure/Force Control status bit will be
set.
Controlling Pressure or Force
Once the axis is in pressure or force control, you can issue any of the pressure/force
commands, including the commands that enter pressure/force control. For example, you
can ramp the pressure up or down, or perform a sinusoidal profile, or follow a spline.
For details on each command, see the respective help topics.
• Ramp Pressure/Force (Rate) (18)
• Hold Current Pressure/Force (19)
• Ramp Pressure/Force (S-Curve) (41)
• Ramp Pressure/Force (Linear) (42)
152 Delta Computer Systems, Inc.