Chapter 2
Installing and Configuring the DAQCard-1200
DAQCard-1200 User Manual
2-4
ni.com
Analog Input Polarity
You can configure the AI setting on the DAQCard-1200 for either a
unipolar range (0 to 10 V) or a bipolar range (–5 to +5 V). If you select a
bipolar range, the two’s complement coding mode is selected. In this
mode, –5 V input corresponds to F800 hex (–2,048 decimal) and +5 V
corresponds to 7FF hex (2,047 decimal). If you select a unipolar mode, the
straight binary coding is selected. In this mode, 0 V input corresponds to
0 hex, and +10 V corresponds to FFF hex (4,095 decimal).
Analog Input Mode
The DAQCard-1200 has three input modes—RSE, NRSE, and DIFF. The
single-ended modes, RSE and NRSE, provide eight input channels. DIFF
input mode provides four input channels. Table 2-2 describes these modes.
While reading the following paragraphs, you may find it helpful to refer
to the
Connecting Analog Input Signals
section of Chapter 3,
, which contains diagrams showing the signal paths for the three
modes. These three modes are software-selectable.
DIFF Input Mode (Four Channels)
DIFF input mode means that each input signal has its own reference, and
the difference between each signal and its reference is measured. The signal
and its reference are each assigned an input channel. With DIFF input
mode, the DAQCard-1200 can monitor four different analog input signals.
Table 2-2.
Analog Input Modes for the DAQCard-1200
Analog
Input Modes
Description
DIFF
DIFF mode provides four differential inputs with the positive input of the
instrumentation amplifier tied to channels 0, 2, 4, or 6 and the negative input tied
to channels 1, 3, 5, or 7, respectively, thus pairing channels (0, 1), (2, 3), (4, 5),
(6, 7).
RSE
RSE mode provides eight single-ended inputs with the negative input of the
instrumentation amplifier referenced to AISENSE/AIGND, which is tied to
ground through about 200
Ω
resistance (default setting).
NRSE
NRSE mode provides eight single-ended inputs with the negative input of the
instrumentation amplifier tied to AISENSE/AIGND, which is not connected to
ground.
