Signal levels for PIN diode are zero

A common cause of this problem (other than the shutter being closed, of course!) is the coupling on the preamplifiers for the detectors. The Femto preamplifiers for the PIN diode and BIM can be set to either AC or DC coupling. They are automatically set to AC coupling when the 7bmb1 IOC is rebooted. To reset the coupling, go to Preamps in the 7-BM-B control screen, open the amplifiers, and toggle the coupling from DC to AC, then back to DC.