User`s manual

1.0 INTRODUCTION
1.1 FUNCTIONAL DESCRIPTION
The PCI-DAS1602/12 multifunction analog and digital I/O board sets a new standard for high performance
data acquisition on the PCI bus. It can sample analog inputs at rates up to 330 kHz. The board provides
16, single-ended, or 8, differential, 12-bit analog inputs, 24 bits of digital I/O, three, 16-bit down-counters.
The PCI-DAS1602/12 has an analog trigger input with trigger levels and direction selectable by software.
In addition, the PCI-DAS1602/12 has two FIFO-buffered 12-bit analog outputs with 250 kHz maximum
update rates.
The PCI-DAS1602/12 is completely plug-and-play. There are no switches, jumpers or potentiometers on
the board. All board addresses, interrupt channels etc. are set by your computer’s plug-and-play software.
Even calibration is performed via software by using on-board digital potentiometers and trim D/A convert-
ers. (For more details on our digital calibration techniques, please see our calibration tutorial on page 74).
1.1.1 Analog Inputs
The PCI-DAS1602/12 provides eight differential or 16 single-ended analog inputs. The input mode is
software selectable, with no switches or jumpers to set. The board offers a 330 kHz maximum sample rate
in single and multichannel scans at any gain setting. A 1024 sample FIFO assures data taken from the
board is transferred into computer memory without the possibility of missed samples.
Software also selects the bipolar/unipolar input configuration as well as selecting among the input ranges.
The table below details the input ranges and resolutions for the available input configurations and gains.
Bipolar Unipolar
Range
Resolution Range Resolution
±10V 4.88 mV 0 to 10V 2.44 mV
±5V 2.44 mV 0 to 5V 1.22 mV
±2.5V 1.22 mV 0 to 2.5V 0.61 mV
±1.25V 0.61 mV 0 to 1.25V 305 µV
1.1.2 Burst Mode
Channel-to-channel skew is the result of multiplexing the A/D inputs and is defined as the time between
consecutive samples. For example, if four channels are sampled at a rate of 1 kHz per channel, the channel
skew is 250 µs (1 ms/4).
Burst mode minimizes channel-to-channel skew by clocking the A/D at the maximum rate between succes-
sive channels. For example, at the 1-ms pulse channel 0 is sampled, channel 1 is sampled 3 µs later,
channel 2, 3 µs after that, and channel 3, 3 µs after that. Then no samples are taken until the next 1-ms
pulse, when channel 0 is sampled again. In this mode the rate for all channels is 1 kHz, but the channel-to-
channel skew (delay) is now 3 µs, or 9 µs total. The minimum burst mode skew/delay on the
PCI-DAS1602/12 is 3 µs.
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