FRS stand-alone system

System architecture

The FRS data acquisition is based on VME electronics, which process the detector signals, according to the trigger logic, digitize and send them to the front-end computer. The standard FRS front-end computer is a RIO4 processor which runs in a Multi-Branch System (MBS) under the Lynux operating system. This RIO4 (named R4-13) resides in the FRS-standard VME crate and is usually consider as the master.

The standard FRS detectors are read out while any user specific detectors should be handled by the user using the other crate, the User one. The standard branch also includes and controls a Camac crate containing the CFDs for MWPC (Multi Wire Proportional Chamber) detectors. The data are usually sent over the GSI Ethernet network to be sample by the on-line analysis clients by means of another processor, the event builder (named X86-11). A view of a single-system architecture is here.
The actual configuration of the FRS-standard VME crate can be found here.
It includes the TPC crate and the S4 crate.
 » FRS trigger

Readout

The VME-based DAQ at FRS were being running and read out normally in single event mode.

When working within the MBS framework, all the individual user has to provide are routines for the initialization and readout of the specific digitizers being used. To this end, a standard init & readout function (f_user.c) has been developed for use with the FRS detector setup. This can be modified in order to include other, user-specific, components (see more about the init & readout function ).
 » Single-event mode

Usually one standard FRS-event readout takes about 110 us, limiting the rate to around 10kHz. A more efficient readout can be performed by using BLock Transfer mode (BLT). A multi-event readout function has been developed and tested.
 » Multi-event mode 

Data visualization

Experience has shown that it is very important to sample and visualize the data stream on-line - i.e. as it is being collected.

To this end, several different software packages can be used, including LeA, Go4 and PAW.

Of these, Go4 represents the latest development, and is recommended by the GSI DVEE department. A Go4 version for general FRS use has been developed. Ask C. Nociforo for the newest version.