ADLINK Technology NuDAQ ACL-8113A, User Manual

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Operation Theorem
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15
4.2 A/D Signal Source Control
To control the A/D signal source, the signal type, signal channel and signal
range should be considered.
Signal Type
The A/D signal sources of ACL-8113A could be single ended (SE) only. The
single-ended mode has only one input relative to ground and it suitable for
connecting with the floating signal source. The floating source means it does
not have any connection to ground. The following figure shows the single-
ended connection. Note that when more than two floating sources are
connected, the sources must be with common ground.
AIN
AGND
n = 0, ..., 31
Floating
Signal
Source
Opertional
Amplifier
To A/D Converter
Input Multipexer
...
V1
V2
Signal Conditioning
Three are 32 SE A/D channels on board. The R/C filters (attenuators) are on
board for every channel. The RC circuits for each channel are shown in the
following diagram, where ‘n’ is the channel number. User can install the R, C
for special purpose such as attenuating the voltage to increase the input
voltage range.
R A n
0. O h m
T o M u l t i p l e x e r A n a l o g I n p u t
C h a n n e l # n
R B n
O P E N
C A n
O P E N
The RC network can also be used as current sensor, which transfers the
current into voltage. To get the ground reference level, user can cut-off RA
and let RB = 0 Ohm, thus grounding the input signal. The users can use the
ground input to calibrate the offset voltage by software.