To debug a problem with the new c1psl (later elog), we needed a Supermicro EPICS server that was using the shared EPICS/modbus/asyn binaries rather than a local install. Of those available in the lab (c1iscaux, c1vac, c1susaux being the others), this was the only one which uses the shared install. So I 

• turned the slow bias voltages to 0
• shutdown the watchdog
• disconnected the Acromag crate in 1X9 from the 192.168.114.xxx subnet at the supermicro end
• connected a test ADC to the local subnet using a different ethernet cable (leaving the original one dangling)
• ran some software tests to see if we could open up a communication line to the test ADC using modbus without any errors being thrown
• removed the test ADC and restored the ethernet connection.

At which point Jon reset the software end, I restored the slow bias voltage and re-enabled the local damping. The optic seems to have damped okay. The Oplev spot is back in ~center of the QPD and the green beam can be locked to a TEM00 mode (so the alignment is okay - the IR beam is unavailable while c1psl issues are being sorted but I judge that things are back to the nominal state now).