Feedback Core Module

Minimal EPICS support module with a small plugin interface for RT feedback tasks with high update rates. Common device-support records, and an analog feedback example for I/O Intr support.

Structure

• Core feedback task and plugin jump table interface
• Common EPICS device-support records for feedback configuration and control
• Generic analog feedback plugin with cached analog input channels
• Example EPICS database for analog feedback records

Documentation

See the documentation in docs/:

• docs/api.md - short C/C++, IOC shell, and database interface reference
• docs/plugin.md - implementing a feedback plugin with the tfbdrvset jump table
• docs/support.md - common feedback device-support modules and record address syntax
• docs/analog_feedback.md - analog feedback plugin startup and callback integration
• CHANGELOG.md - notable changes for releases and publishing

Getting Started

Build

# Create configure/RELEASE file
# This sets default path to EPICS base:
./configure.pl
# build the module
make -j

Set up the IOC using the built-in analog example support

In the startup script, after loading the application DBD, but before iocInit(), add:

dbLoadRecords("db/feedback_analog_example.db", "IOC_NAME=example")
dbLoadRecords("db/feedback_control_example.db", "IOC_NAME=example")

fbAnalogInitPlugin
fbInit 0,0,0,4,0,0,100,100

After iocInit(), start the feedback loop from the IOC shell:

fbOpen 1

Alternatively, start it through EPICS records:

# set soft sample rate
caput example:setSoftTaskRate 100

# start the feedback task
caput example:open 1

# monitor the generated example output
camonitor example:AI0 example:AI1 example:AI2 example:AI3

fbAnalogInitPlugin registers and activates the generic analog feedback plugin. The example fbInit call configures analog channels 0..3, input node 0, rate 100 Hz.

See examples/feedback_analog_example.db for a minimal analog feedback input database example.

See examples/feedback_control_example.db for a minimal feedback control database example.

Compatibility

This module is intended to stay compatible with Linux, VxWorks 5.4, EPICS 3.14.12.x, and EPICS 7.

Dependencies

EPICS Base 3.14.12.x or higher and VxWorks 5.4 only when building for legacy VxWorks targets.

Contributing

Contributions are welcome. Please keep changes small, focused, and compatible with the supported EPICS and VxWorks versions.

Before submitting a change:

• build the module on the platforms available to you;
• keep C/C++ code compatible with old GCC/C89-style VxWorks builds;
• update the relevant documentation in docs/;

Any feedback is welcome for larger changes.

References

• ** STATUS OF THE CONTINUOUS MODE SCAN FOR UNDULATOR BEAMLINES AT BESSY II ** A. Balzer, E. Schierle, E. Suljoti, M. Witt, HZB, Berlin, Germany R. Follath, PSI, Villigen, Switzerland Proceedings of ICALEPCS 2015
  https://www.helmholtz-berlin.de/media/media/forschung/wi/optik-strahlrohre/mono/icalepcs2015-thha3o02.pdf

License

MIT License. See LICENSE.