Spectrum Controls SLC 500 User Manual page 26

3-4 Chapter 3: Configuring the 1746sc-INI4I
Filter Frequency
Current Input
Voltage Input
(-INI4vi only)
For a 16-bit device like the 1746sc-INI4i and -INI4vi, a worst-case effective resolution of 12 bits means
1
that the data may fluctuate by as much as 16 counts (4 bits). Typically, the effective resolution is greater
than that listed here
User's Manual Pub. 0300128-04 Rev. A
time, as shown in the following tables.
Table 3-1. Cutoff Frequency, Step Response Time, and Effective Resolution
(Based on Filter Frequency)
Worst-Case Effective Resolution
Filter 3dB Cutoff
50 Hz 13.1 Hz
60 15.7
250 65.5
500 131
Table 3-2 Channel Update Time (Based on Number of Channels Enabled and
Filter Frequency)
Number 50 Hz
of
channels
enabled
1 20.0 ms
2 20.5
3 19.8
4 21.0
2 20.5
1 19.7 ms
2 19.7
3 19.7
4 19.7
The 3 dB cutoff 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.
1
Full-Scale Voltage
Step Mode
Response
80 ms 12 bits
66.7 12
16 11.5
8 9.5
60 Hz 250 Hz
16.6 ms 4.0 ms
17.7 7.3
16.6 10.6
17.0 13.8
17.7 7.3
16.6 ms 5.0 ms
17.2 9.2
16.6 13.5
18.0 18.0
Current
Mode
11 bits
11
10.5
9.5
500 Hz
4.1 ms
7.3
10.7
13.8
7.3
5.0 ms
9.2
13.5
18.0