Appendix a: glossary – B&B Electronics 4 Channel Input Buffer Board SDAIBB User Manual
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SDAIBB3599 Manual
A-1
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Appendix A: Glossary
Common Mode Voltage
( )
CM
V
: The voltage about which a differential
voltage swings. When this is measured on the SDAIBB it is calculated
with all voltage readings taken in reference to GND of the SDAIBB as
(
)
2
−
+
+
IN
IN
. Note that when one of the inputs is connected to GND of
the SDAIBB the common mode voltage changes as the differential voltage
changes.
Differential Voltage
(
)
DIFF
V
: The difference in voltage across two points
such as the two leads on a thermocouple. When this is measured on the
SDAIBB it is calculated with all voltage readings taken in reference to
GND of the SDAIBB as
−
+
−
IN
IN
.
Gain
( )
G : The amount by which the input is multiplied before it is output.
−
+
−
=
IN
IN
V
Gain
out
Impedance Mismatch: When the output impedance of sensor is different
enough from the input impedance of the data acquisition device to cause
improper sensor readings.
Negative Input Differential: When the voltage and IN- is higher than the
voltage at IN-.
0
≤
−
−
+
IN
IN
Negative Rail: The lowest possible voltage that can be output. For the
SDAIBB there is a negative rail internal to the buffer and a negative rail on
the output of the buffer.
Positive Rail: The highest possible voltage that can be output. For the
SDAIBB there is a positive rail internal to the buffer and a positive rail on
the output of the buffer.