The Clamshell Daemon: clamd

The Clamshell Daemon (clamd) interfaces with the i/o box controller clamshell lines. It can issue commands to open or close the clamshell, and can query the clamshell limit switches to determine if the clamshell is open, closed or in transition. If a limit switch opens or closes unexpectedly, clamd will try to issue a close command and will shut down the system.

One should note that operating the clamshell with the manual external switch is incompatible with the normal operation of the daq system. If the system (specifically spotd, described in Section 1.2.3) is not running, then the watchdog module will not allow the clamshell to be opened. If spotd is running, any unexpected change in the clamshell status caused by opening limit switches will log a fatal error, and the system will shut down. The external clamshell switch only is useful in early set-up stages of the telescope.