Target plate control
There are remote controlled target plates deployed along the arms of the interferometer. The controller of each plate accept a TTL signal to move the plate up and down. There are 8? targets in one arm, thus totalling 16? targets to be controlled.
Interlock Signal from Interferometer
The interferometer provides interlock signals to shut down the laser in case of, for example, some optics swinging too large or mis-aligned too much. The trigger conditions are programmed into the realtime system (thus out of the scope of instrument control). The generated trigger signal will be sent to the instrument control system via TTL lines. The physical connectors for the trigger signals will be provided at three places, the central area and the two end stations. At each of the three locations, all the various trigger signals/conditions are aggregated to a single TTL line. Therefore, the instrument control system should expect to receive one TTL line per location for the trigger from the interferometer.
Interlock Signal from Facility
The facility subsystem may emit interlock signals to the laser for various reasons. The most probable scenario is that an unauthorized person entering the KAGRA site triggers a warning from the access control system. We expect to have a few (less than 10) TTL lines sent from the facility to the instrument control system for this purposes.