IOtech DaqBoard/3000USB Series, Руководство пользователя

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1-6 Device Overviews
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DaqBoard/3000USB Series User’s Manual
Signal I/O
One 68-pin connector provides access to the 16SE/8DE analog input channels, 24 digital I/O lines,
counter/timer channels, and analog outputs (when applicable). Redundant connectivity is found in four 40-
pin headers; two of which provide each DaqBoard/3031USB and /3035USB board with expansion
capability for having a total of 64 single-ended [or 32 differential] channels.
Reference Note :
In regard to analog expansion, refer to the J5 and J6 pinouts in chapter 2.
Analog Input
Each DaqBoard/3000USB Series board has a 16-bit, 1-MHz A/D coupled with 16 single-ended, or 8
differential analog inputs [up to 64 SE or 32 DE for /3031USB and /3035USB boards]. Seven software
programmable ranges provide inputs from ±10V to ±100 mV full scale. Each channel can be software-
configured for a different range, as well as for single-ended or differential bipolar input. Each differential
channel can accept any type of thermocouple input.
Synchronous I/O
The DaqBoard/3000USB series has the ability to make analog measurements and scan digital and counter
inputs. In addition, DaqBoard/3001USB and /3031USB boards can synchronously generate up to four
analog outputs.
Additionally, while digital inputs and counter inputs can be synchronously scanned along with analog
inputs, they do not affect the overall A/D rate because they use no time slot in the scanning sequencer. For
example, one analog input can be scanned at the full 1-MHz A/D rate along with digital and counter input
channels. The 1-MHz A/D rate is unaffected by the additional digital and counter channels.
Input Scanning
DaqBoard/3000USB Series devices have several scanning modes to address a wide variety of applications.
A 512-location scan buffer can be loaded by the user with any combination of analog input channels. All
analog input channels in the scan buffer are measured sequentially at 1 µsec per channel. The user can also
specify that the sequence repeat immediately, or repeat after a programmable delay from 0 to 19 hours,
with 20.83 nsec resolution. For example, in the fastest mode, with a 0 delay, a single analog channel can
be scanned continuously at 1 Msamples/s; two analog channels can be scanned at 500K samples/s each;
16 analog input channels can be scanned at 62.5 Ksamples/s.
The digital and counter inputs can be read in several modes. First, via software the digital inputs or
counter inputs can be read
asynchronously at anytime before, during, or after an analog input scan
sequence. This software mode is not deterministic as to exactly when a digital or counter input is read
relative to an analog input channel.
In either of the two synchronous modes, the digital inputs and/or counter inputs are read with deterministic
time correlation to the analog inputs. In the
once-per-scan mode , all of the enabled digital inputs and
counter inputs are read during the first analog measurement of an analog input scan sequence. The
advantage of this mode is that the digital and counter inputs do not consume an analog input time slot, and
therefore do not reduce the available bandwidth for making analog input measurements. For example,
presume all 24 bits of digital input are enabled, and all four 32-bit counters are enabled, and eight channels
of analog inputs are in the scan sequence at full 1µsec/channel rate. At the beginning of each analog input
scan sequence, which would be 8 µsec in total duration, all digital inputs and counter inputs will be
measured and sent to the PC during the first µsec of the analog scan sequence.