I noticed this morning that dust monitor 9, which had previously been dropping in and out of communication, was no longer coming back. I went out and looked at it, but didn't notice anything obvious. I also managed to smack my head on one of the light pipes between the H1 PSL enclosure and HAM1.

I connected to the IOC screen, pressed Start on the medm for the dust monitor, and got a read timeout reported by the IOC.

I then trended the mode back, which should oscillate from 'holding' to 'running' every minute, to see when communication was lost. Seeing that it stopped yesterday, I compared it to dust monitor 8, which I had turned off and removed yesterday. The two times are in close agreement (see attached plot).