ICS PCI-AOB2 Series, User Manual

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Introduction 1-1
Chapter 1
Introduction
Features
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2, 4, or 6 Channels of Analog Output, 12 Bits Resolution.
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16 Digital I/O Lines Buffered on the Card.
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Digital I/O Buffers Can Be Tri-stated under Program Control.
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Pull-Ups on Digital I/O Lines.
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Resettable fused +5V and +12V Supplies
Available to the User.
Description
The PCI-AOB2/4/6 is a half-size card that can be installed in any PCI slot of PC-AT class
computers. It contains two, four, or six double-buffered digital-to-analog converters
(DACs) that provide independent analog output channels of 12-bit resolution. Each
analog output channel can be configured for ranges of:
0V to +2.5V
0V to +5V
0V to +10V
-2.5V to +2.5V
-5V to +5V
-10V to +10V
4mA to 20mA
The analog output channels have a double-buffered input for single-step update and each
is addressed at its own I/O location. Type AD7237 double-buffered, dual, DAC chips are
used. Data are transferred into outer registers a byte at a time (eight LSB's then eight
MSB's) and then transferred into inner registers a word at a time. The analog outputs can
be updated either independently or simultaneously.
The DAC outputs are undefined at power-up. Therefore, in order to prevent excessive
outputs to external circuits, the PCI-AOB2/4/6 contains automatic circuits that set D/A
outputs to less than 15 percent of span at system power-on. Upon power-up, the card is in
the Simultaneous Update mode. After all DACs have been loaded with the desired values,
a software command can be used to switch the reference voltage to its normal value.
Similarly, a software command can be used at any time to set the reference voltage to 15