CDS: execute one CDS cycle

This page is part of the ING document INS-DAS-24: client-server interface for control of cameras

Purpose: perform one correlated-double-sample cycle and store the resulting pixels.

Actors: udas_run client; udas_camera server; camera.

Outline: the client invokes the READOUT action. The server orders the camera to read out once. As the pixels arrive from the camera, the server captures and stores them, demultiplexing the pixel-stream during the readout to save processing time.

Normal course of events:

Client invokes the READOUT action on the server with these arguments:

Argument1 is the number of readouts before and after integration, set to 3.
Argument2 is the integration time, in seconds, set to 5.0.
Argument3 is the preflash time, inseconds, set to 0.3.
Argument4 is the type of integration, set to "expose".

Server does the equivalent of the CLEAR action (q.v.).
Server does the equivalent of the READOUT action (q.v.) with Argument1 set to 1 and Argument2 set to 3.
Server does the equivalent of the PREFLASH action (q.v.), with Argument1 set to 0.3.
Server does the equivalent of the INTEGRATE action (q.v.), with Argument1 set to "expose" and Argument 2 set to 5.0.
Server does the equivalent of the READOUT action (q.v.) with Argument1 set to 2 and Argument2 set to 3.
Server returns good status to client.

Variations:

Client varies the integration time. Any time greater or equal to zero is acceptable; negative times are rejected.
Client varies the number of readouts. Negative or zero counts are rejected. Counts greater than 2 + UDAS_MAX_RUN_ROS/2 (where UDAS_MAX_RUN_ROS is a compile-time constant set in udas_limits.h) are rejected.
Client puts "dark" instead of "expose" for Argument4. Server uses this value when emulating the INTEGRATE action.

Notes:

As will be obvious from the text above, this action does nothing that cannot be done by a sequence of other actions. The composite CDS action is provided to speed up the events and to reduce communications delays.