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BNC-2120 Installation Guide
Measuring Resistance
You can measure resistance with the analog input screw terminals on the BNC-2120. Figure 4
is a schematic representation of how the BNC-2120 measures resistance.
Figure 4.
Measuring Resistance on the BNC-2120
RES+ is internally connected to AI 3 and V
CC.
RES– is internally connected to AI 11. There is
also a 10 k
Ω
resistor between AI 11 and AI GND.
When connecting signals to the screw terminals, use 28–16 AWG wire with the insulation
stripped to 0.28 in.
Complete the following steps to measure resistance.
1.
Move the RES/BNC switch above the AI 3 BNC to the RES position.
2.
Configure your software to measure AI 3 and AI 11 in referenced single-ended (RSE)
mode.
3.
Connect the resistor to the RES+ and RES– screw terminals.
You can measure resistors with values ranging from 100
Ω
to 1 M
Ω
.
4.
Measure V
CC
on AI 3 and the voltage drop across the internal 10 k
Ω
resistor on AI 11.
5.
With these measurements, calculate the resistor value using the following formula:
Connecting Analog Output Signals
Use the AO <0..1> BNC connectors on the BNC-2120 front panel to connect analog output
signals to your DAQ device.
1
The number of connectors you use depends on your DAQ device
and application. Refer to your DAQ device documentation for information about the use of these
signals.
1
When using the BNC-2120 with Connector 1 of two connector M/X Series devices, the AO <0..1> BNCs
on the BNC-2120 map to the AO <2..3> channels on the device.
RES+
AI 3
BNC-2120
V
CC
User Resistor
AI 11
AI GND
AI SENSE
RES–
AI
Resistor Value
V
AI 3
V
AI 11
–
V
AI 11
10 k
Ω
(
)
⁄
---------------------------------------
=
