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Chapter 4 Theory of Operation
© National Instruments Corporation 4-11 PCI-1200 User Manual
The recommended DAQ rates in Table 4-2 assume that voltage levels on all
the channels included in the scan sequence are within range for the given
gain and are driven by low-impedance sources.
Analog Output
The PCI-1200 has two channels of 12-bit D/A output. Each analog output
channel can provide unipolar or bipolar output. The PCI-1200 also contains
timing circuitry for waveform generation timed either externally or
internally. Figure 4-5 shows the analog output circuitry.
Figure 4-5.
Analog Output Circuitry
Analog Output Circuitry
Each analog output channel contains a 12-bit DAC. The DAC in each
analog output channel generates a voltage proportional to the 10 V internal
reference multiplied by the 12-bit digital code loaded into the DAC. The
voltage output from the two DACs is available at the DAC0OUT and
DAC1OUT pins.
You can program each DAC channel for a unipolar voltage output or a
bipolar voltage output range. A unipolar output gives an output voltage
range of 0.0000 to +9.9976 V. A bipolar output gives an output voltage
range of –5.0000
to +4.9976 V. For unipolar output, 0.0000 V output
corresponds to a digital code word of 0. For bipolar output, –5.0000 V
output corresponds to a digital code word of F800 hex. One LSB is the
DAC0
DAC1
DAC0OUT
AGND
DAC1OUT
EXTUPDATE*
10 V Internal
Reference
DAC0WRT
Data
DAC1WRT
Counter
A2
External Update
8
I/O Connector
Two's Complement
Two's Complement
PCI Bus
Digital
Control
Logic
MITE
PCI
Interface
Chip
Data/Address
Interface Control
Error Reporting
Arbitration
System
Interrupt
1
2
2
2
6
37
Address
Data
Control
Interrupt
1
4
8
5