32
Operation Theory
NOTES
• The maximum A/D sampling rate is 250 kHz for PCI-9222 and 500
kHz for PCI-9223. The minimum setting for the SI2_counter when
using the internal Timebase is 320 (PCI-9222) and 160 (PCI-9223).
• The SI_counter is 32-bit while the SI2_counter is 24-bit. The maxi-
mum scan interval using the internal Timebase = 2
32
/80 Ms =
53.687s, and the maximum sampling interval between two chan-
nels using the internal Timebase = 2
24
/40 Ms = 0.419s.
• The scan interval must not be smaller than the product of the data
sampling interval and the NumChan_counter value. The relation-
ship can be represented as: SI_counter>=SI2_counter *
NumChan_counter.
Specifying Channels, Gains, and Input Configurations in the
Channel Gain Queue
The channel, gain, and input configurations can be specified in
the
Channel Gain Queue
under the scan acquisition mode.
Note that in scan acquisition mode the number of entries in the
Channel Gain Queue is normally equivalent to the value of
NumChan_counter (the number of samples per scan).
Example:
Set
X
SI2_counter = 160
X
SI_counter = 640
X
PSC_counter = 3
X
NumChan_counter = 4
X
Timebase = Internal clock source
X
Channel entries in the Channel Gain Queue: ch1, ch2,
ch0, ch2
Then:
X
Acquisition sequence of channels: 1, 2, 0, 2, 1, 2, 0, 2, 1, 2,
0, 2
X
Sampling Interval = 160/80M s = 2 us
X
Scan Interval = 640/80M s = 8 us
X
Equivalent sampling rate of ch0, ch1: 125 kHz
X
Equivalent sampling rate of ch2: 250 kHz
Summary of Contents for NuDAQ PCI-9222
Page 12: ......
Page 36: ...24 Hardware Information...
