ADLINK Technology NuDAQ PCI-9114DG, User Manual, Page: 39 / 95

Operation Theorem
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differential analog signal input connection. By differential input mode, the
common mode noise on AIHn and AILn will be deducted.
AIn
IGND
n = 0, ...,31
Signal
Source
Opertional
Amplifier
To A/D
Input Multipexer
...
V1
V2
Figure 4.1 Signal sources and single-ended connection
AIHn
AILn
n = 0, ..., 8
Ground
Signal
Source
To A/D
V G 1 V G 2
Vcm = VG1 - VG2
GND
+
-
Figure 4.2 Grounded source and differential input
Signal Channel Control
There are two ways to control the channel number. The first one is the
software programming and the second one is the auto channel scanning
which is controlled by the ASCAN bit in AD trigger mode control register. As
ASCAN is cleared (0), the value of AD Channel Control register defines the
channel to be selected.
As ASCAN is set 1, the value in AD channel control register defines the ending
channel number of auto -scanning operation. Under auto scan mode, the
channel is scanning from channel 0 to the ending channel. Whenever a
trigger signal is rising, the channel number to be selected will increase
automatically. For example, if the ending channel number is 3, the auto
channel scanning sequence is 0,1,2,3,0,1,2,3, …, until the ASCAN bit is
cleared.