J. Garcia, J. Kissel

Now that we finally have a functional system with centered OSEMs at all stages for the H2 SUS ITMY and H2 SUS FMY, we've changed the watchdog values to be more stringent (as in actually protecting the system). See aLOG 1264 for details on the three types of watchdogs.
 
For all OSEM stages on both suspensions, we've set the limits as

OSEM DC LO: 100
OSEM DC HI: 30000

Justification: The DC watchdog watches the raw ADC inputs of the OSEMs. The possible range should be between 0 cts (when the flag is completely blocking the LED) and the open light current, close to the ADC limit of 32768. During normal operation, the OSEMs should be centered to around 15000 counts, and typically do not move +/- ~5000 from the centered position. However, at some point, adding a DC offset, or losing the bouyancy of the SUS in vacuum, (for example) may cause this center position to change. So, we pad the extremes a little bit, and go with the above values.


OSEM AC: 20000

Here, there's not too much experience with this value, but typical undamped RMS velocities are something around 1000 cts, and during drives something like 10000 cts. So, we'll continue to think about what a good value for this is.


ACTUATOR: 80000

Here the OSEMs don't have the drive strength to really do any damage, and we have a 18 bit DAC, so 120000 cts to play with. Typical levels for damped system are ~2000 cts, and for drive during transfer functions, around ~10000 cts.

Finally -- remember that the safest state for the suspension is to have damping loops ON. So we want the watchdog to trip only on super extreme cases. This is why it may seem we're being gracious with our thresholds.