CAEN V767 128 Channel Gen. Purpose MH TDC - Physics

02/07/2003 V767 User's Manual – Rev.4
3.4. OUTPUT BUFFER
(Base address + %0000 read only; from firmware rev 2.0 accessible also at Base +
%2000 ÷ + %FFFC)
The output buffer contains the output data organised in 32-bit words. The data in the
buffer are organised as follows:
A) In the case of Start Trigger Matching, Stop Trigger Matching (Common Stop
Emulation included) and Start Gating mode the data in the buffer are organised in
events.
Each event consists of (refer to Fig. 3.4):
• a header that contains the event number value;
• the data words containing the 20 bit converted time values, the channel number
and an edge bit;
• an End Of Block (EOB) word containing the number of data words (i.e. the
HEADER and EOB are not included) and a Status that is 1 if the TDC Chips
have had an error, 0 otherwise.
B) In the case of Continuous Storage mode there are neither the header nor the EOB
word, but only the data words.
In both cases, if a read access is performed to the buffer when it is empty, the readout
will provide a NOT VALID DATUM arranged as shown in Fig. 3.4.
N.B.: in the Mod. V767B which does not have the JAUX, the GEO address
contained in the HEADER and in the EOB must be written by the user via a write
access to the relevant register (see § 3.5). If this operation is not performed, it will
be not possible to identify which module the data are coming from when the CBLT
access is used.
HEADER
GEO
HEADER
1
0
EOB
EVENT NUMBER
DATUM
CHANNEL
HEADER
0
0
EOB
TIME MEASUREMENT
START
EDGE
EOB
GEO
HEADER
STATUS
0
1
EOB
EVENT DATA COUNTER
HEADER
NOT VALID 1 1
DATUM
EOB
EVENT NUMBER
Fig. 3.4: Mod. V767 Output Buffer Data Structure
NPO:
00001/97:V767x.MUTx/04 Page 28 of 75