Delta RMC151 - Manual (Page 201)

3 Controller Features
1. Determine Actual Measurement Versus Transducer Measurement
Determine the equation that defines the relationship of the desired measurement to the
transducer's measurement. The machine designer should be able to provide a formula.
2. Define Custom Axis and Reference Axis
a. Define a control axis with the feedback type required (position, velocity, pressure,
force, or acceleration). For the feedback source, choose Custom.
b. Create a reference axis for the physical feedback input to be used.
c. Configure the feedback parameters for the reference axis and verify that the
transducer gives valid readings.
d. Set the Scale and Offset so that the reference axis provides correct values
throughout the entire range.
3. Create a User Program
a. Create a user program with an Expression (113) command, and Jump Link Type set
to Repeat.
b. In the expression, enter the formula and assign the value to the control axis' Custom
Counts register.
c. Set the CustomErrorBits.NoTrans bit according to the state of the active feedback. This
can be done by using the Feedback OK status bits of the reference axes.
For example:
4. Make Sure the User Program Always Runs
As described in more detail in the Custom Feedback topic, do the following:
a. Set the RMC to start in RUN mode.
b. Use a _FirstScan condition in the Program Triggers to start the user program when the
RMC enters RUN mode.
c. Make sure the Task does not stop when an axis halts.
5. Tune the Axis
Tune the axis manually (auto-tuning does not work in RUN mode).
3.10.5. Redundant Feedback using Custom Feedback
Redundant feedback can be implemented in the RMC by using Custom Feedback. When the
controller detects that one transducer has problems, it can immediately switch to another
feedback on the fly, even in the middle of motion. The user has the flexibility to program the
logic that determines which feedback should be used, making redundancy using any number
of transducers possible.
Tip: The Examples section of Delta's online forum includes a Redundant Feedback example.
You can use that example to help you get started.
Setting Up Redundant Feedback
Read the Custom Feedback topic before completing this procedure.
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