CAEN
Electronic Instrumentation
UM3148
–
DT5730/DT5725 User Manual rev. 2
30
•
TRIGGER TIME TAG
(Bit[31:0] of 4
th
header word)
= It is the 31-bit Trigger Time Tag information (31-bit counter
and 32
nd
bit as roll over flag), which is the trigger time reference. If the ETTT option is enabled, then this field
becomes the 32 less significant bits of the extended 48-bit trigger time tag information in addition to the 16 bits
(MSB) of the TRG OPTIONS field (2
nd
event word). Note that, in the ETTT case, the roll over flag is no more
provided. The trigger time tag is reset either as the acquisition starts or via front panel signal on GPI connector,
and increments with 125-MHz frequency (every 4 ADC clock cycles in case of DT5730 or 2 ADC clock cycles with
DT5725). The trigger time tag value is read at half this frequency (62.5 MHz). So, the trigger time tag
specifications result in 16 ns resolution and 17 s range(i.e. 8 ns*(2
31
-1)), which can be extended to 625 h (i.e. 8
ns*(2
48
-1)) by the Extended Trigger Time Tag option.
Data
are the samples from the enabled channels. Data from masked channels are not read.
Event Format Example
Tab. 9.3
shows the event data format of DT5730/DT5725 when all the 8 channels are enabled. The structure is
described in §
Event Structure
.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7
6 5
4 3 2 1 0
EVENT SIZE
TRIGGER TIME TAG
1
0
1
0
RES.
EVENT COUNTER
SAMPLE [1]
– CH[0]
SAMPLE
[0]
– CH[0]
SAMPLE [3]
– CH[0]
SAMPLE
[2]
– CH[0]
SAMPLE [N-1]
– CH[0]
SAMPLE [N-2 ]
– CH [0]
SAMPLE
[1]
– CH[1]
SAMPLE
[0]
– CH[1]
SAMPLE
[3]
– CH[1]
SAMPLE [2]
– CH[1]
SAMPLE [N-1]
– CH[1]
SAMPLE [N-2 ]
– CH [1]
H
E
A
D
E
R
D
A
T
A
C
H
0
D
A
T
A
C
H
1
SAMPLE [1]
– CH[7]
SAMPLE [0]
– CH[7]
SAMPLE [3]
– CH[7]
SAMPLE [2]
– CH[7]
SAMPLE [N-1]
– CH[7]
SAMPLE [N-2 ]
– CH [7]
D
A
T
A
C
H
7
BOARD -ID
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
PATTERN
CHANNEL MASK [7:0]
RESERVED
RESERVED
BF
RESERVED / TRG OPTIONS
RES.
0
Tab. 9.3:
Event Format Example