The CCUSB Readout framework provides support for the Wiener-JTec CC-USB CAMAC controller. The CC-USB is a USB CAMAC controller that uses a Xilinx gate array to implement a CAMAC list processor. The CCUSB Readout framework provides:
A high level approach to the problem of data taking with the CC-USB
Support for user written device support without any need to understand the format of list operations supported by the CC-USB. Drivers can be written in either C++ or in object oriented extensions to Tcl.
Direct insertion of data taken to an arbitrary destination ringbuffer.
Support for use as a data source with the NSCL event builder.
This Chapter provides overview information that describes
The philosophy behind the CCUSB readout framework.
How to write configuration files for the CCUSB readout framework.
How to write device support modules in in C++ and incorpoprate those modules into the CCUSB readout framework
How to write device support modules in Tcl and incorporate those modules in the CCUSB readout framework.
How the slow controls framework operates.
How to write slow controls drivers in C++
How to write slow controls drivers in Tcl
How to integrate the CCUSBReadout program with the state manager.
Reference information is available in the 3ccusb section of the referencae material.
The CCUSB readout framework provides a high level approach to configuring devices supported by the system. A plugin architecture allows user written device support to be incorporated into the framework at run-time.
The framework supports both data taking devices and slow control devices that may require a control panel. Naturally you can support relatively static slow control devices by using the data taking device support as well.
The recurring concepts for both the data taking device support and slow controls device support are:
A Tcl configuration file describes the devices used by the experiment.
Each supported device class is represented in the configuration file by a Tcl command ensemble. The command ensemble provides subcommands that allow you to create, configure and query the configuration of physical devices (device instances).
The device configuration is represented in the configuration file in manner analagous to the state of a Tk widget. That is, you never actually program the device directly, you simply specify the desired configuration. The actual programming is done by the device class's device support software.
In accordance with the way the CC-USB operates, you can create two lists or stacks in CC-USB parlance. One stack is an event stack and is intended to be used to handle event triggers. The second stack is a scaler stack and typically is set to readout periodically.
Each stack has, configuration properties as well. One configuration property is the set of modules managed by that stack. Modules managed by that stack are initialized by the software, in accordance with their configuration, and contribute to the readout list that executes in response to that stack's trigger.