The CATCH module is the standard readout-module within the COMPASS experiment. This is the module which directly connects to the front-end boards and thus has to provide flexibility for different detector electronics. The input to the CATCH main board is done through four CATCH mezzanine cards, built according to the CMC standard. These boards are generic and can connect to a variety of physical links (e.g. HOTLink, Vitesse, optical or copper). We also have built mezzanine cards with TDC chips and cards with fast deadtime-free scalers. As an example for such a CMC card a HOTLink mezzanine card is shown in the figure above.

Each HOTLink Mezzanine card controls four front-end boards and receives data at a maximum transmission rate of 40 MByte/s. The data from up to four Mezzanine cards (i.e. 16 front-end boards) are sorted according to the event number and then combined to sub-events. The framed data are transmitted to the ROBs via S-LINK at a speed of 100 MByte/s (160 MByte/s with the new generation of S-LINK cards). Additionally an independent spy buffer can be used to access a fraction or all of the events via the VME bus at a lower rate. This allows for an easy setup of a standalone DAQ without S-LINK and spill buffer, e.g. at test beams.

The VME-interface is used to control and initialise the detector mounted front-end electronics. Data to the front-end can be downloaded at a rate of 10 MBaud. An experiment-wide synchronisation signal (38.88 MHz) as well as trigger signals and event information is received from the Trigger Control System (TCS). The experiment clock, time-zero synchronisation and the trigger signals are distributed to the front-end boards.

For the COMPASS test beam in September 1999 and the development of the front-end electronics 10 CATCH-X prototypes have been produced. The CATCH-X is designed similar to the CATCH but as a 6U VME-module. This constrains the number of mezzanines cards (e.g. CMC-HOTLink) to one and requires the S-LINK card to be mounted on the main board as a mezzanine card, since there is no P3 connector on 6U VME crates. The choice of the 6U size for the CATCH-X prototypes was driven by the larger availability of such crates in the associated laboratories.

• June 1998: A prototype CATCH1 board without S-Link was tested successfully.

Figure 2: Overview of the CATCH1 6U VME module.




• February 1999: CATCH-X in design phase.
• June 1999: To learn more about S-LINK a SLIDAD was connected to the CATCH1 multipurpose 80 pin test-pattern connector via a short cable and a simple adapter PCB.
• July 1999: Design review with S-LINK developer E. van der Bij.
• July 1999: Production of PCB for 10 CATCH-X.
• August 1999: Production and test of the 10 CATCH-X.
• September 1999: COMPASS testbeam at M2. Successful readout of a scintillating fibre detector with a 32 channel TDC-CMC mounted on top of the CATCH-X.

  
  

• October 1999: CATCH in design phase.
• May 2000: Production of PCB for 30 CATCH modules.
• July-September 2000: Use of CATCH at COMPASS commissioning run.

Figure 3: The CATCH 9U VME module mounted with four 32 channel F1-TDC cards.

• Januar 2001: Small revisions of PCB Layout.
• March 2001: Production of final CATCH.
• June-October 2001: Use of about 85 CATCH modules in COMPASS data taking. For S-LINK the 100 MByte/s cards as well as the new ODIN cards (128 MByte/s and 160 MByte/s) are used.

• CATCH and CMC-HOTLink Readout Driver Specification,
• Presentation given at LEB98 (hep-ex/9810048)
• Presentation given at Pisa meeting 2000
• Presentation given at RT2001
• Developments of readout electronics at Freiburg University
• COMPASS Home Page
• COMPASS DAQ Pages

• Fritz-Herbert Heinsius
• Horst Fischer

CERN - CERN High Speed Interconnect - CERN S-LINK
Fritz-Herbert Heinsius - 17 October 2001