Geometry events are less important with the production readout boards: the data headers are expected to contain this information eventually, and the new MiniDAQ can exploit this. Further, the geometry will usually be kept in a standard configuration.
However, geometry events are still used by the off-line analysis, and to debug the electronics and sector hardware. Normally, one would take geometry events with MiniDAQ, as discussed below. However, the data are also available through slow controls.
One can take geometry events as 8 or 10-bit data, and in native or pad-mapped formats. The 8-bit, mapped format is normally recommended, since any bits beyond eight are meaningless and must be masked off, and the mapped format is simplest to understand.
Time bucket values are replaced with the FEE card location for the cards that are plugged. The test anode-wire readout card is a special case and returns 200. If an FEE is not present, the location appears as 255. Values read from non-existent RDO locations (i.e., locations beyond the end of a truncated RDO) are currently random garbage, but the intention is to pull up the data lines to 255.
Geometry events are now fully supported by MiniDAQ and Run Control, and are selected at ``configure'' time, as for any other run type. In principle, the same information is also available through the Slow Controls HDLC link, but is not described here.
Written: November 10, 1996 by R.Bossingham
Last modified: April 21, 1997 by R.Bossingham
Roy Bossingham, LBNL