Chapter 3: Architecture
29
Analog Input Subsystem
The analog input front-end multiplexes multiplex the first stage of the
input channels (64/16 single-ended or 32/8 differential) into a single,
12, 14 or 16-bit successive approximation ADC. The A/D subsystem also
includes input modes, polarity, gain settings, channel gains, channel
queue, trigger and clocking control.
MF boards have multiplexors located at the signal inputs and can be
switched to select single ended (SE) or differential (DF) mode of
operation (Fig 8). SE/DF mode is selected for all input channels. The
output of the mux signal is fed into a instrumentation amplifier (INA)
and then into a custom programmable gain amplifier (PGA). Channel
numbers along with their gains are stored in the channel list. This allows
you to select different gains on a per-channel basis.
Note
Input muxes have high input impedance. It is highly
recommended to ground all unused channels. Use
signal sources with low output impedance (<100
Ohms) to avoid crosstalk; place a capacitor between
signals and ground (SE) or between signal and
return lines on screw terminal (suggested capacitor
values can be 1000pF to 0.047uF depending on your
input frequency).
Summary of Contents for PD2-MF
Page 5: ...Table of Contents iii Index 137 ...
Page 11: ...1 1 Introduction ...
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Page 19: ...9 2 Installation and Configuration ...
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Page 35: ...25 3 Architecture ...
Page 63: ...53 4 PowerDAQ Software Development Kit PD SDK ...
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Page 107: ...97 5 Calibration ...
Page 109: ...99 A Appendix A Specifications ...
Page 110: ...Appendix A Specifications 100 ...
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Page 113: ...103 B Appendix B Accessories ...
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Page 119: ...109 C Appendix C Application Notes ...
Page 125: ...115 D Appendix D Warranty ...
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Page 129: ...119 E Appendix E Glossary ...
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