ADLINK DAQe-2214 - Manual (Page 46)

34 Operation Theory
Scan with SSH
You can send the SSHOUT signal on CN2 to external S&H cir-
cuits to sample and hold all signals if you want to simulta-
neously sample all channels in a scan, as illustrated in
Figure 4-1.
NOTE The SSHOUT signal is sent to external S&H circuits to
hold the analog signal. You must implement external
S&H circuits on their own to carry out the S&H function.
There are no onboard S&H circuits.
Specifying Channels, Gains, and Input Configurations in
the Channel Gain Queue
Like software polling acquisition mode, 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 nor-
mally equivalent to the value of NumChan_counter (that is, 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: 160/40 Ms = 4 µs
X
Scan interval: 640/40 Ms = 16 µs
X
Equivalent sampling rate of ch0, ch1: 62.5 kHz
X
Equivalent sampling rate of ch2: 125 kHz