Chapter 2 Installation and Configuration
DAQCard-1200 User Manual 2-6 © National Instruments Corporation
Analog Output Polarity
The DAQCard-1200 has two channels of analog output voltage at the front
panel I/O connector. You can configure each analog output channel for
either unipolar or bipolar output. A unipolar configuration has a range of
0 to 10 V at the analog output. A bipolar configuration has a range of –5 to
+5 V at the analog output. If you select a bipolar range for a D/A conversion
(DAC), the two’s complement coding is selected. In this mode, data values
written to the analog output channel range from F800 hex (–2,048 decimal)
to 7FF hex (2,047 decimal). If you select a unipolar range for a DAC, you
are selecting the straight binary coding. In this mode, data values written to
the analog output channel range from 0 to FFF hex (4,095 decimal).
Digital I/O Configuration
The DAQCard-1200 uses the MSM82C55 programmable peripheral
interface (PPI). This chip provides 24 digital lines in the form of
threep orts—A, B, and C. On power up, all three ports reset to high
impedance inputs. For information about configuring the MSM82C55,
seethe D AQ Timing Connections section of Chapter 3, Signal
Connections.
Caution The DAQCard-1200 DIO lines are not pulled up or pulled down. If you are using
these lines as digital outputs, add 10 k
Ω

ΩΩ

Ω
resistors to +5 V or DGND (depending on
your application) to the DIO line(s) you are using.
Counter Configuration
You can use the MSM82C53A counter/timers for general-purpose timing
applications, such as pulse and square wave generation, event counting,
and pulse-width, time-lapse, and frequency measurement. For information
about configuring the MSM82C53A, see the DAQ Timing Connections
section of Chapter3, Signal Con nections.
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