While investigating the 2 Hz comb in DARM, Sheila and Patrick found communications errors with beckhoff at EY. The End Station 2 Ethercat chasssis was brought back to the lab for further troubleshooting. Spare unit was installed and Beckhoff computer was restarted. While troubling shooting the unit found a bad EK1100 coupler on the third rail (left) of the chassis. Re-scanned unit and found 5 terminals all EL3104 (anaolog inputs) that were giving us errors. After re-scanning/checking internal cabling/power cycling, we were only able to reproduce 3 errors. We tried multiply times to try and reproduce all five errors, but could not. Eventually after a power cycle, all errors we had previously seen could not be reproduce. After multiple re-scans and power cycles with no errors showing up, we used a voltage calibrator and injected a 5V DC signal into the EL3104 terminals. It was later decided to reinstall unit back at EY.
Once we installed the spare EtherCat chassis, the ETMY ring heater was outputting less than the requested power (first plot). (H1:TCS-ETMY_RH_UPPERPOWER and H1:TCS-ETMY_RH_LOWERPOWER were 0.34 and 0.2 W respectively, instead of the requested 0.5W.) Trending the ring heater input channels showed this change happened during the chassis swap. It appears there was a 0.2W bias on H1:TCS-ETMY_RH_UPPERCURRENT and H1:TCS-ETMY_RH_LOWERCURRENT.
When we swapped the original chassis back in, the ETMYring heater output the correct power (second plot).