User manual

Programmer’s Guide Page 26 of 64
- Each Gate will start with a Gate Descriptor which describes the length of the gate and its position relative to the
trigger of the segment.
-If a segment does not contain any valid data, there will not be any Gate Descriptor or Gate Data, the next Segment
Descriptor will follow immediately.
3.6.4.1. Segment Descriptor
The Segment Descriptor is always 8 words (256 bits) and has the following format: 31 30 29 28 27 26 25 24
23 22 21 20 19 18 17 16 15 14 13 12
31 .. 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
Header Tag= 0x00
reserved
reserved
reserved
reserved
nbrGates
reserved
reserved
D
C
T
reserved
reserved
reserved
reserved
TimeStampHigh [15..0]
TimeStampLow [31..0]
Item
bits
Description
Header Tag 8
A value of 0x00 indicates this is a segment descriptor of type1. A
segment descriptor of type 1 is always 8 words (256-bits).
nbrGates 32 Indicate the exact number of gates that has been found in the segment.
The end of each segment can only be determined by counting the number
of gates read (nbrGates).
TimeStampHigh
TimeStampLow
48 TimeStamp is the value of the time counter when the trigger occurs. The
time counter can be reset to zero through the software user interface. The
resolution of this counter will depend on which model and sampling rate
is being used, please refer to the product datasheet for details.
3.6.4.2. Gate Descriptor
Each Segment Descriptor is followed by zero or more Gate Descriptors, as indicated in the Segment Descriptor's
nbrGates field. The Gate Descriptor has the following format:
31 .. 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
Header Tag= 0x01
gateLength [23..0]
gatePos [31..0]
Item
bits
Description
Header Tag 8 A value of
0x1 indicates this is a gate descriptor of type1. A gate
descriptor of type 1 is always 2x4 bytes. The content is as described in
this table.
gateLength 24 Number of samples that follow the gate descriptor. Possible values are
0x10 modulo 0x10 when the module is operating in 2 channel mode (2 x
2 GS/s non-
combined) and will be 0x20 modulo 0x20 when the module
is operating in single channel mode (1 x 4 GS/s combined).
gatePos 32 Absolute position of the first sample of the pre-gate data relative to the
trigger of the segment, indicated in number of samples, this value may be
used to reconstruct the data.