[Yamamoto, Ushiba]
We faced the hung up of HWP during increasing laser power.
The problem can be solved by rebooting rasbery-pi.
In case of IFO REFL HWP, we have a rebooter, so we just rebooted it from medm screen.
In case of PSL HWP, we don't have rebooter, so we logged in the rasbery-pi with ssh command, and reboot it.
We are not so sure what triggered the problems but we need to fix it for stable 10W operation.
The log during the trouble is shown in fig1.
I prepared a button on the MEDM screen to reboot RaspPi for which a rebooter was not installed yet as shown in Fig.1.
To distinguish from a reboot button by the rebooter, button color is changed from another HWPs.
Because it's still a temporal implementation, we need to input a password 3 times.
According to the past experiences, we always received an error message from the HWP script when HWP became unavailable. This means that a problem related to HWP occurs on an USB connection between RaspPi and HWP not a SSH connection between workstations and RaspPi. (If RaspPi itself hangs up, we should receive a message from SSH such as "connection refused", "no route to host", and so on.) So sending a reboot command via SSH is enough for recovering HWP instead of the rebooter. Though we need to some tests, even the reboot command is not necessary and unbinding/re-binding USB devices might be enough for this issue. If so, a HWP script can do it by itself and recovering HWP can be automated.
