Chapter 3
DMM Operation
DAQMeter DAQCard-4050 User Manual
3-10
©
National Instruments Corporation
Continuity Measurements
Many traditional multimeters can make continuity measurements,
which test for the presence or absence of continuity between the two test
probes. These measurements are simply resistance measurements,
where the resistance between the two probes is measured and compared
to a set value. You can perform continuity measurements on a circuit by
setting the DAQCard-4050 to the 200
Ω
range and comparing the
measured value to some low resistance value (10
Ω
is typical). If the
measured value is less than 10
Ω
, there is continuity between the test
probes.
Testing Diodes
You can also use the DAQCard-4050 to measure the forward drop
across a diode. You can measure voltage drops of up to 2 V.
Signal Connections
Connect the test probes to a diode as shown in Figure 3-4. To accurately
measure the forward voltage of a diode, make sure that the diode is not
connected to any other circuits. The DAQCard-4050 biases the diode
with a current of 100
µ
A and measures the resulting voltage drop. Diode
measurements are made with a fixed range of 2.0 V and an accuracy of
0.01%.
Figure 3-4.
Connections for Diode Measurement
Diode
+
-
100
µ
A
250 V
MAX.
LO
HI
