R&D (FilterCavity)
EleonoraCapocasa - 17:42, Thursday 25 October 2018 (1035)
Telescope control CPU swapped

[Eleonora, Matteo, Yuhang]

On Mon 22 we found out that the supervisor PC used for Labview control system was not able to connect to the CPU (NM2 for TM: 133.40.121.78)which manages the ADC and DAC for the telescope suspended mirrors (PR and BS).

We checked this CPU (which is in the central area) and find out that it was not possible to swich it on anymore. Futher investigations suggested that the problem was in  the power supply unit.

So we removed the CPU, DAC and ADC units from it and insert them into the power box of another unused remote target, after removing its CPU (NM2 for IP: 133.40.121.73) and ADC/DAC units.
 
We could smoothly connect the supervisor PC to it and acquire and generate signals with ADC and DAC, but we observed a very strange behavior:  the frequencies at the output of the DAC are divided by two, with respect to those that we expected to send, while the frequencies read by ADC are multiplied by two. This suggest that the internal timing was two time faster than the correct one.
 
I went to the west end room and collect two other unused target computers. One of them could not be switched on (EM1 for IP: 133.40.121.71) the other one was working fine (EM1 for TM: 133.40.121.77). I have used the power box of this one to power the telescope CPU and everything worked fine and the timing problem was solved.
 
Since it is unlikely that the timing problem can come from the power box, I suspect that we might have not connected all the cables properly, the first time.
 
Summary: the power box of the telescope mirrors CPU was borken, we replaced it with another one and everything now works fine.