EPICS database for control system feedback API

[prjemian]

• Close #1
• Close #6

[prjemian]

@keenanlang Do you know how to set the busy PV automatically to unknown after some time period (a few seconds, perhaps)? I assume there might be a keep_alive PV that bluesky will need to keep setting to keep the timer from expiring.

[prjemian]

keep alive feature watches for the python process to be stuck or quit

• IOC has an incrementer calc (10 Hz)
• Once incrementer (on change) reaches threshold (20-60 seconds), set the busy PV to 0
• python background process pushes 0 to the incrementer counter at 1-2 Hz

[prjemian]

example of stop & start the soft IOC:

(bluesky_2022_1) prjemian@zap:~/.../bdp_controls/feedback$ ./bpd_feedback.sh stop
Stopping 117556.bpd_feedback (pid=117558)
(bluesky_2022_1) prjemian@zap:~/.../bdp_controls/feedback$ ./bpd_feedback.sh start
Starting bpd_feedback with IOC prefix bpdfb:
Old : bpdfb:action 
New : bpdfb:action 
Old : bpdfb:status 
New : bpdfb:status EPICS bpd_feedback IOC started
(bluesky_2022_1) prjemian@zap:~/.../bdp_controls/feedback$ !caget
caget -S bpdfb:{busy,action,status}
bpdfb:busy                     unknown
bpdfb:action 
bpdfb:status EPICS bpd_feedback IOC started
(bluesky_2022_1) prjemian@zap:~/.../bdp_controls/feedback$ ./bpd_feedback.sh status
118888.bpd_feedback is running (pid=118890) in a screen session (pid=118888)

[prjemian]

Thanks!