Delta RMC101 - Manual (Page 559)

Analog 6.1
Transducer Interface Modules 6-15
type.
Step 3: Set the Scale A and Offset A Parameters for the Pressure Inputs
Refer to the individual field sections for details on setting these parameters.
Analog Input Ranges
See the COUNTS topic for detailed information on the maximum and minimum limits of the
various analog input ranges.
See also:
Analog Transducer Overview
Analog Transducer Wiring
Analog Transducer Configuration
Using Analog Channels as Position Inputs
Using Analog Channels as Velocity Inputs
Using Analog Channels as Differential Force Inputs
6.1.7.4 Using Analog Channels as Differential Force Inputs
Differential force control uses two separate analog channels as pressure inputs to generate one
force reading. Both inputs are scaled to forces, and then one is subtracted from the other, giving
a final differential force.
Notice that force and pressure are not interchangeable terms. This is because it is only
acceptable to subtract pressures if the surface areas acted on by the pressure are equal. In a
typical hydraulic cylinder with a single-ended rod, this is never the case because the rod takes up
part of the surface area on one side of the cylinder.
Analog channels may be configured to be used as one of two differential force input types. Both
require the Pressure Control firmware option:
• Differential Force Control
Two pressure inputs are used with the corresponding drive output (in this mode, analog modules
without drive outputs cannot be used for pressure control) for closed-loop, differential-force
control. See Controlling Solely Position, Pressure, or Force for details.
• Auxiliary Differential Force
The inputs do not have their own drive output. However, differential force control is achieved by
sharing a drive output of another input. This is used in applications where an axis switches
between closed-loop position control and closed-loop differential-force control. See Transitioning
from Position to Auxiliary Pressure/Force Control for details.
The following general steps are necessary for setting up differential force inputs:
Step 1: Assign Analog Channels to be an Differential Force Input
To assign a pair of analog channels to be a differential-force input, do the following: