34
Operation
Figure 3-9: 2-wire RTD Connection
3.3.6
Wire Resistance Mode
The USB-2401 can source precision 0.05 mA excitation current to
the resistor to be measured and use a 2.5V input range to acquire
cross-voltage on the resistor. The formula of voltage to resistance
conversion is:
Since the excitation current can only drive the cross-voltage up to
1.5V with good linearity, the maximum equivalent value of the
resistor is limited to 30k
.
ADC
MUX
0.5mA
RTD
X
X
X
X
SC+
SC-
EXC
GND
USB-2401
0.00005
V(volt)
)
(
=
Ω
R
Summary of Contents for USB-2401
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Page 22: ...12 Introduction Figure 1 3 USB 2401 Module Side View...
Page 23: ...Introduction 13 USB 2401 Figure 1 4 USB 2401 Module Front View 41 3 114...
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Page 26: ...16 Introduction Figure 1 8 Module Stand Top View 20 4 20 4 B 26...
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