1. DAQ & data format Peter Fischer Institut für Technische Informatik, Universität Mannheim Presentation given at the EUDET / JRA-1 review, 4.4.2006, Geneva

2. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 2 Introduction  We have decided to use the present DEPFET DAQ as a starting point.  Note: This DAQ has been written with a minimum effort, so –not enough documentation –still hard coded stuff –some error checking, no ‘recovery’ (but good enough)  This starting point must be improved: –need a clever way for process communication (across operating systems?) –need a ‘global controller’ –need a better way to request Monitoring data –need ‘shared buffer through TCP/IP’ –…  This cannot be done by Mannheim (or Bonn), it is not our task, neither are we real experts…

3. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 3 Present DEPFET ‘Mini-DAQ’  PC based, at the moment Windows based. Very light weight.  DAQ Software is divided into many parallel tasks: –several Producer tasks read the hardware –one FileWriter task bundles events, writes to file and sends subsets for monitoring –There can be several Online - Monitoring tasks –one Buffer Monitor task allows to see what is going on –a FileReader can re-inject data into the monitoring  Central data flow element: ‘shared buffers’ –Used between Producers and Writer and between Writer and Monitors –Events have unambiguous trigger ID in the buffers for later sorting –Mutex elements are used to control access of the buffers –Uses begin-of-run (BORE), data (DATA), end-of-run (EORE) events.

4. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 4 Present DEPFET ‘Mini-DAQ’ Hardware Writer task telescope ‘producer’ task DEPFET ‘producer’ task other ‘producer’ tasks Monitoring task 1Monitoring task 2 DAQ buffers Monitoring buffers file

5. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 5 Shared Buffers  Organize data transport between tasks.  Two types: –DAQ buffersfrom DAQ tasks to WRITER –Monitoring Buffersfrom WRITER to MONITORING tasks  Two port buffer: one task can write, one task can read (no checks!)  Very simple & efficient: –~300 lines of source code for class implementation –writing & reading can be done simultaneously, arbitration only needed at start / end of transfers. –data blocks are always contiguous blocks of data so that tasks do not have to bother with wrapping pointers in ring buffers  Can be extended to send data from PC to PC (via TCP/IP)  Buffers are created by the writing task. (If they already exist, the task connects to the existing buffer)  Buffers automatically disappear when nobody refers to them any more.

6. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 6 Shared Buffer header (part) class TSharedBuffer { static const unsigned int MAX_SHARED_BUF; public: TSharedBuffer (AnsiString Name, unsigned int Size, SBufferType Type = BUFTYPE_DAQ); ~TSharedBuffer (); bool Created; // flags if buffer was newly created or already existed bool IsEmpty (void); float GetFillLevel (void); // return fill level unsigned int * GetWriteAddress (unsigned int BlockSize); // request a pointer to write void FinishWrite (unsigned int * NextPos); // flag that we are done unsigned int GetDataSize (void); // see how much data is there unsigned int * GetReadAddress (unsigned int * Size); // get data address (and size) void FinishRead (unsigned int * NextPos); // release data until NextPos void Clear (void); // delete all data... }

7. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 7 data structure in the shared buffers  one word = unsigned integer (32 bit)  data is organized in events with a 2 word header: -word 0: event typebegin of run BORE end of run EORE dataDATA event size(including header)size event contentgroup dataGROUP detector datadevice / module / flags -word 1:trigger numberstart with 0, magic numbers for BORE/EORE -word 2…size:size-2 data words

8. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 8 present bit allocation 3128272423222120 0 Event Type: 0x0: BORE 0x1: EORE 0x2: DATA 0x3: unused Device Type: GROUP TELESCOPE DEPFET 13 x unused TLU ? 310trigger 310 0 data word 1 data word 2 310data word N word 1 word 2 word 3 word N+2 19 Size (including header) = N+2 Module Flags

9. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 9 packets in the buffers DAQ buffer (single events): BORE - info word BORE trigger = magic BORE word BORE data 1 BORE data N DATA- info word event #1 0x00000000 DATA data 1 DATA data N DATA- info word event #2 0x00000001 DATA data 1 DATA data N EORE - info word EORE trigger = magic EORE word EORE data 1 EORE data N monitoring buffers and file (GROUP Events!): BORE - info word: GROUP type BORE trigger = magic BORE word BORE 1 BORE N event #1 event #2 EORE DATA - info word: GROUP type 0x00000000 DATA event 1 DATA event N DATA - info word: GROUP type 0x00000001 DATA event 1 DATA event N EORE - info word: GROUP type trigger = magic EORE word EORE event 1 EORE event N                                                  

10. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 10 BORE and EORE events  BORE (Begin Of Run Event): –time, date, … –detector configuration data (bias values, thresholds, pedestals, …)  EORE (End Of Run Event): –error flags –statistics for consistency checks (total number of data words,…) –…

11. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 11 GROUP events  GROUP events are used to bundle data for ONE TRIGGER from several sources.  They are written to file and sent to the monitoring tasks.  data events within GROUP events are identical to full single events (i.e. headers are not stripped) –this gives a small overhead, as trigger ID is repeated –but it makes copying and analysis much simpler

12. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 12 example of possible ‘advanced’ data flow USB DUT1 hardware DUT DAQ PC - WIN (beam area, via VNC) PCI VME telescope DAQ PC - LIN (beam area, via VNC) CAMAC main PC - WINDOWS (counting room) DUT2 hardware telescope hardware TDC hardware writer Mon 1 Producer TCP MON PC - LINUX (remote) TCP Mon 2

13. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 13 Demo 1.Buffer Monitor + file writer  fill levels, raw data format 2.Add file writer  Observe emptying of buffers and BORE, EORE mechanism 3.Add monitoring task  Modify Producer parameters  restart a new run  two monitoring tasks 4.Have a look at source code (?)

14. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 14 Deliverables (to Daniel, David, Gilles,… ?)  shared buffer class  event class, derived DEPFET event class  Applications written in C++ under Borland CBuilder (Windows): –BufferMonitor –DEPFET_DummyProducer –FileWriter –DEPFET_OMO –TEST_OMO  A fair amount of comments in the code…

15. EUDET JRA1: DAQ starting pointPeter Fischer, Uni Mannheim, Page 15 Summary  Pipelined operation  Small tasks keep units simple  Clearly defined interface at buffer ends  Extensions are simple  flexible choice of operating system  Several small monitoring tasks can run in parallel  Later: –Preprocessed data (tracks) can be included into the data flow and be used by monitoring tasks. This requires some modifications, but sounds like a very interesting option! –Send buffers through TCP/IP (work in progress) to relief main DAQ computer  Still needed: –Overall control task (flush all buffers, start/stop run,…) –Sending stuff over TCP/IP –Better control over detector configuration –Logfile –…