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--- sweeper_usb_daq_data_format [2017/05/07 16:59]
pereira [VME Crate data format]
+++ sweeper_usb_daq_data_format [2017/06/11 17:26] (current)
pereira [The Sweeper USB DAQ data format]
@@ Line 1: / Line 1: @@
 ====== The Sweeper USB DAQ data format ======
-Two crates are read by the Sweeper DAQ software (one CAMAC and one VME), but more could be easily added to the software. This section describes the data format coming from each controller. (Please, note that this data format  is irrelevant for the user; this is so because the USB data are "pre-unpacked" by the [[Pre-unpacker|Sweeper Pre-unpacker]] software before being distributed to the user.)
+Two crates are read by the Sweeper DAQ software, one CAMAC and one VME. Data from each of these controllers are pushed into [[http://docs.nscl.msu.edu/daq/newsite/nscldaq-11.2/c43.html|ring buffers ]] (**rawccusb** for CCUSB and **rawvmusb** for VMUSB). The Sweeper Event Builder (EVB) reads  data from these ring-buffers, correlates them on the basis of their time stamps, and outputs the resulting data stream on the ring buffer **sweeper**. According to the NSCLDAQ 11.x [[http://docs.nscl.msu.edu/daq/newsite/nscldaq-11.2/x4509.html|format]], data in the ring buffer **sweeper** will be organized in ring items, each consisting of two fragments, one for each controller.
+The structure of the data from the Sweeper EVB is schematically illustrated in the figure below:
+{{:wiki:diagram_ringitem_fromevb.png?800|Schematic representation of data format from Sweeper EVB}}
+Events from the Sweeper EVB will be encapsulated in ring items, consisting of header, a body header, and a body. The body part contains two fragments, one from each controller. Each fragment has a header, followed, again, by a ring item (with its corresponding header, body header, and body).
+The structure from the body of each fragment is described below in some detail. Please, note that this data format  is irrelevant for the user; this is so because the USB data are "pre-unpacked" by the [[Pre-unpacker|Sweeper Pre-unpacker]] software before being distributed to the user.

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