ADLINK USB-1903 - Manual (Page 54)

40 Operation
Timebase Clock Source
In scan acquisition mode, all A/D conversions start with the out-
put of counters using the timebase as the clock source.
Through the software, you can specify the timebase as the
internal clock source (onboard 80 MHz).
Three trigger sources are available to start the scan acquisi-
tion. Refer to Section 4.3: Trigger Sources for details. For data
transfer mode, please see Section 4.2.4: Continuous Acquisi-
tion (Scanning) Mode.
X
The maximum A/D sampling rate is 250 kHz. The minimum
setting for the SI2_counter when using the internal time-
base is 320.
X Both the SI_counter and SI2_counter are 32-bit. The maxi-
mum sampling interval between two channels using the
internal timebase = 2
32
/80 Ms =53.687s for single channel
data acquisition.
X The scan interval must not be less than the product of the
data sampling interval and the NumChan_counter value.
The relationship 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 Scan Acquisition mode.
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).