The shutter.sch schematic

The records on this schematic allow the user to open or close the shutter on the wavefront sensor CCD stage. The shutter dictates whether an image of the lenslet arrays can be detected at the NAOMI SDSU camera system.

The output signals required to open or close the shutter are sequenced by the gensub record on this schematic. The user must select the desired shutter state ("open" or "closed") at the soft-channel binary input record "bi". The transition is enacted by sending a START directive to the cad record, which will process the gensub "gsb" on this schematic.

• If the XYCOM-240 output from binary output record "bo0" is not low, the shutter cannot remain open. Therefore, if the user requests a closed shutter, "bo0" is used to change this output to high.

• To open the shutter, "bo0" is directed low. This will not, in itself, open the shutter. The signal from binary output record "bo1" is pulsed low for a fixed time, which should open the shutter.

Note: at the time of this writing, an additional soft-channel binary input record is in place in the schematic, but not shown on this page. This enables the user to specify that the software will or will not check the shutter state after an open/close operation. At present, the shutter status feedback hardware is faulty.