National Instruments DAQPad-1200, Руководство пользователя

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Chapter 2 Installing and Configuring the DAQCard-1200
DAQCard-1200 User Manual 2-6 ni.com
Analog Output Polarity
The DAQCard-1200 has two channels of AO voltage at the front panel I/O
connector. You can configure each AO 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, the
two
’ s complement coding mode is selected. In this mode, data values
written to the AO channel range from F800 hex ( – 2,048 decimal) to 7FF
hex (2,047 decimal). If you select a unipolar range, you are selecting the
straight binary coding. In this mode, data values written to the AO channel
range from 0 to FFF hex (4,095 decimal).
Configuring Digital I/O
The DAQCard-1200 uses the MSM82C55 programmable peripheral
interface (PPI). This chip provides 24 digital lines in the form of
three ports
— A, B, and C. On power up, all three ports reset to
high-impedance inputs. For information about configuring the
MSM82C55, Refer to the
Analog Input Timing Connections section of
Chapter 3, Connecting the Signals .
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 resistors to +5 V or DGND (depending on your
application) to the DIO line(s) you are using.
Configuring Counters
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 measurements. For information
about configuring the MSM82C53A, refer to the
Analog Input Timing
Connections section of Chapter 3, Connecting the Signals .