Chapter 3
NI 4350 Operation
3-2
©
National Instruments Corporation
The 4-wire ohms mode has six corresponding input ranges when used
with the built-in 25
µΑ
current source: 25 k
Ω, 50
k
Ω, 100
k
Ω, 150
k
Ω,
300
k
Ω,
and
600
k
Ω.
Choose the smallest range for the best
measurement results
.
Note:
With VirtualBench, the NI435X instrument driver, or the DAQ Channel
Wizard, you can specify the range based on your sensor type in engineering
units appropriate to the sensor.
Choosing a Reading Rate
The reading rate is the rate at which your NI 4350 takes a new
measurement. This rate has a direct relationship with the digital filter
built into the ADC used in the NI 4350.
The digital filter has the characteristics shown in Figure 3-1. You can
set the frequency of the first notch of this filter to 10 Hz, 50 Hz, or
60 Hz. Setting the notch filter at one of these frequencies rejects any
noise at that frequency as well as at all its multiples.
Figure 3-1.
Digital Filter Characteristics for 10 Hz Setting
0
–20
–40
–60
–80
–100
–120
–140
–160
–180
–200
–220
–240
Gain (dB)
Frequency (Hz)
0
10
20
30
40
50
60
