> We had a case where a detector produced electrostatic discharges which only lasted for a second or so
> and we were happy to detect this in spikes in the HV current. With measurements of only one per minute
> we would not have realized that so quicky.
For the T2K/ND280 TPC we implemented something similar. The TPC uses MicroMegas detector which sparks during
normal operation. We asked Wiener/ISEG to implement a "spark counting mode" for us (and they did). In this mode,
high voltage over-current (a micromegas spark) sets a special flag (does not trip the high voltage). Our midas frontend
reads this flag at rate about 1/min, if flag is set, clears it, increments the software spark counter, reads the flag again,
if the flag is still set (failed to clear), it means this was not a normal spark but a high voltage breakdown
and the offending channel is shut down. I believe this mode is still part of the ISEG normal firmware.
Because the Wiener/ISEG interface uses SNMP to "read all data in one operation", the MIDAS "device driver" structure
was not useful, the readout was a simple loop, the readout frequency was easy to control, and indeed,
we read the high voltage with increased frequency during ramping. This was easy to implement because we
did not have to fight the MIDAS "device driver" framework.
If you want a similar solution, talk to the device, interpret the data, record values to odb and history, generate
midas events - all without hand holding from (arm wrestling with the rest of) midas - I recommend
the new tmfe.h/tmfe.cxx c++ frontend - see the two examples in midas/progs/fetest_tmfe.cxx
and fetest_tmfe_thread.cxx (single-threaded and multi-threaded).