Manual, F/T Sensor, Ethernet Axia
Document #9620-05-C-Ethernet Axia-02
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C-27
5.3 Sample Rate
The power-on default sample rate is the rate a user sets before removing power. The sample rate is stored to
nonvolatile memory. The ADC rate controls the current sample rate. The following table lists the rounded
and exact sample rates.
Table 5.5—Sample Rate
Rounded Sample Rate
0.5 kHz
1 kHz
2 kHz
4 kHz
8 kHz
Exact Sample Rate
488 Hz
976 Hz
1953 Hz
3906 Hz
7912 Hz
5.3.1 Sample Rate Versus Data Rate
The data rate is how fast data can be output over the Ethernet interface.
If the data rate is faster than the sample rate, the customer sees duplicate samples output over the
network until the next sample is read internally. A faster data rate could be useful so that the sensor
sends data at the same rate that other devices in a customer’s system are outputting. For example: if
a device on the same application as the Axia is outputting data at 7,000 Hz, the customer may want
the Axia to be outputting data to the network at 7,000 Hz as well, even though the sensor is not
sampling that quickly internally.
If the sample rate is faster than the data rate, the customer does not receive the data from every
internal sample over the network. However, any filters that are enabled work based on the faster
internal sample rate, and so the sensor filters out higher frequency noise sources than if the filter is
operating at a slower data rate.
5.4 Low-Pass Filter
The power-on default selection is “no filtering.” Users can issue a filter command via one of the Ethernet
software interfaces to control the current filter selection. The cutoff frequency (for example: -3 dB
frequency) is dependent on the sample rate selection, which is defined in
cutoff frequencies for the different sampling rates are listed in the following table.
Table 5.6
—Low-Pass Filtering
Selected
Filter
-3dB Cutoff Frequency (in Hz)
at 488 Hz
Sample Rate
at 976 Hz
Sample Rate
at 1953 Hz
Sample Rate
at 3906 kHz
Sample Rate
at 7912 Hz
Sample Rate
0
200
350
500
1000
2000
1
58
115
235
460
935.10
2
22
45
90
180
364.04
3
10
21
43
84
169.52
4
5
10
20
40
81.24
5
2.5
5
10
20
39.84
6
1.3
3
5
10
20.31
7
0.6
1.2
2.4
4.7
9.37
8
0.3
0.7
1.4
2.7
5.47
