Operation
29
times the equivalent source impedance, such that if the source
impedance is less than 100Ω, the negative side of the signal needs only
be connected to GND as well as the negative input of the
Instrumentation Amplifier without any resistors. Connection of a
floating signal source to the USB-62401 in differential input mode is as
shown.
Figure 3-3: Floating Source and Differential Input
3.3.2
Current Input Mode
Current signal source can be floating or grounded reference,
converted to voltage through a precision 249.5Ω resistor.
Cross-voltage on the precision resistor is considered differential signal.
The differential signal pair passes through differential amplifier
buffers and is measured by the analog-to-digital converter chip (ADC)
with ±2.5 V input range.
The formula to calculate voltage-to-current conversion is:
6701527
.
18
)
(
)
(
volt
V
mA
Current
=
Summary of Contents for USB-62401
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Page 21: ...Introduction 11 Figure 1 3 USB 62401 Module Side View...
Page 22: ...12 Introduction Figure 1 4 USB 62401 Module Front View...
Page 24: ...14 Introduction Figure 1 7 Module In Stand Front View...
Page 25: ...Introduction 15 Figure 1 8 Module Stand Top View 20 4 20 4 B 26...
Page 29: ...Introduction 19...
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Page 34: ...24 Getting Started Figure 2 4 Module Pre Rail Mounting Figure 2 5 Module Rail Mounted...
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Page 43: ...Operation 33 Figure 3 7 4 Wire RTD Connection Figure 3 8 3 Wire RTD Connection...
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Page 62: ...52 Getting Service...
