User manual

Programmer’s Guide Page 62 of 64
Extra
Type
300 / sampInterval + 98
digitizers with
≤
1 GS/s maximum sampling rates
300 / sampInterval + 194 digitizers with 2 GS/s maximum sampling rates or DC271-FAMILY
instruments set for a combine channel mode allowing 2 GS/s
300 / sampInterval + 386
DC271-FAMILY instruments set for a 4 GS/s combine channel mode
5. The copying time Cpy per 8-bit sample is ~ (5 µs) / (Pentium CPU speed in MHz).
Thus, for a 250 MHz Pentium Cpy is ~ 0.02 µs, and for a 500 MHz Pentium it is ~ 0.01 µs.
Benchmarks were run on 266 and 550 MHz Pentiums, running under Windows 98 and NT. The observed transfer
times agreed with the formula within better than 20%.
• dataType=3:
Add the conversion time T
3
for conversion from ADC codes to Volts, to T
2
or T
1
respectively:
ConvNMT ⋅⋅=
3
where Conv is the conversion time per sample in microseconds. It is ~ (35 µs) / (Pentium CPU speed in
MHz). Thus, for a 250 MHz Pentium Conv is ~ 0.14 µs, and for a 500 MHz Pentium ~ 0.07 µs.
4.2. Examples
(A) DP210 in a 800 MHz Pentium:
Transferring single records of 100'000 samples, recorded at 2 GS/s:
672
192
480125
.3
5
.62
00625.
001
.0
000
1001
=
+=
==
=
=
==
Extra
OvhdOvhd
CpyXfr
NM
bufferDMA
sXfrNMOvhdMT
DMA
µ 106310005.62
1
=+=⋅⋅+⋅=
( )
s
CpyNMXfrExtraNMOvhdMOvhdT
bufferDMA
µ 169800625.000010001.0672100125.35.62
2
=⋅+⋅++=
⋅⋅+⋅+⋅+⋅+=
It is therefore more favorable to use the function AcqrsD1_readData for readMode = 0.
Transferring 100 segments of 1000 samples, recorded at 2 GS/s:
672192480
125
.35.62
00625
.
001
.0
0001100
=+=
==
===
=
ExtraOvhdOvhd
CpyXfrN
M
buffer
DMA
s
XfrNMOvhdM
T
DMA
µ 725001.01000
1005
.
62100
1
=⋅⋅+
⋅=⋅⋅+⋅
=
(
)
s
Cpy
NM
XfrExtra
NM
OvhdM
OvhdT
buffer
DMA
µ
267200625
.0
0001100
01.
0672
1100125
.3
1005
.62
2
=⋅
⋅+
⋅⋅+
⋅+
=
⋅⋅+
⋅+
⋅+
⋅+
=
The function AcqrsD1_readData for readMode = 1 (ReadModeSeqW) is about 2.7 times faster.