Spectrum Controls 1746sc-INI4vi - Manual (Page 27)

Chapter 3: Things To Consider Before Using Your Module 23
Table 9. Channel update time
(based on number of channels enabled and filter frequency)
Filter Frequency
# of ch. enabled 50 Hz 60 Hz 250 Hz 500 Hz
Current Input 1 20.0 ms 16.6 ms 4.0 ms 4.1 ms
2 20.5 17.7 7.3 7.3
3 19.8 16.6 10.6 10.7
4 21.0 17.0 13.8 13.8
Voltage Input (-INI4vi only) 1 19.7 ms 16.6 ms 5.0 ms 5.0 ms
2 19.7 17.2 9.2 9.2
3 19.7 16.6 13.5 13.5
4 19.7 18.0 18.0 18.0
The 3 dB cut-off frequency is the frequency at which input signals are
passed with 3 dB of attenuation.
Choose a filter frequency so that the frequency of your fastest changing
signal is lower than that filter’s 3 dB cut-off frequency. All frequency
components above the 3 dB cut-off frequency are increasingly
attenuated, as shown in the following figures.
Figure 6. Signal attenuation with 50 Hz input filter
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0 50 100 150 200 250 300 Hz
-3 dB
13.1 Hz
Amplitude (in dB)
Signal Frequency