The NBI generation 3 camera system (CCD3) (Fig.1) consists of two major components, - the CCD3-controller that is clamped onto the unit containing the detector ( usually a kind of dewar), and a PCI-card, - normally hosted inside a PC. One or more of each of these units are interconnected by an optical fibre, - either point to point or in a ring-shaped configuration, allowing more units to be inserted within the same optical ring (OptoRing).
Each controller is a small self contained unit that cannot be expanded. The internal power supply supports up to 16 video channels and 96 clock drivers. If larger systems are needed, the controller is equipped with a syncronisation mechanism, allowing a cluster of controllers to work together as one unit.
The OptoRing supports simultaneously transfer of bulk data (pixel data) and single characters with full handshake (commands). This command channel enables continuous exchange of commands and status between acquisition software in the host computer and software running local in the controller by means of an assisting uP on the sequencer-board. To facilitate this operation a set of commands and status-requests is defined, - the CCD3-command-set.