Rockwell Automation 1794-OF8IH FLEX Isolated Input/Output HART Analog Modules - Manual (Page 51)

Publication 1794-UM065B-EN-E - September 2010
1794-IF8IH and 1794-OF8IH Configuration 39
Input Filter Cutoff (8 of 3 bits)
ADC Filter Frequency for channel. This parameter affects channel accuracy:
See the table below.
Data Table Reference: filter cutoff, Configuration Words 4…7, bits 0…2,
8…10.
ADC Conversion Rate, Channel Update Time and Repeatability
The following table shows the channel update time, channel settling time,
repeatability, 50 Hz normal mode rejection and 60 Hz normal mode rejection
for each A/D conversion rate. The repeatability is based on six-sigma RMS
noise levels.
Data Format (8 of 4 bits)
Specifies the module data format. Formats 2, 6 and 8…15 are not assigned. If
they are selected, a configuration failure will be declared. The configuration is
not accepted and the last valid configuration will be used.
Formats 5, 12, 13 and 14 are 2's complement data formats, and will return data
in that form.
Accuracy vs Filter Cutoff
Filter Cutoff
7
(1)
6
(1) 5 4 3 2 1 0 (Default)
Frequency n/a n/a 470 Hz 62 Hz 19.6 Hz 16.7 hz 10 Hz 4.17 Hz
Word Setting n/a n/a 101 100 011 010 001 000
(1)
For settings of 6 & 7 the module will return a configuration error and remain in the last properly configured state.
ADC Conversion Rate Effects
A/D
Conversion
Rate Channel
Update
Time Channel
Settling
Time Repeatability 50 Hz
Rejection 60 Hz
Rejection
4.17 Hz 240 msec 480 msec 0.12
μ
a 74 dB 74 dB
10.0 Hz 100 msec 200 msec 0.23
μ
a 69 dB 69 dB
16.7 Hz 60 msec 120 msec 0.31
μ
a 80 dB
19.6 Hz 51 msec 101 msec 0.35
μ
a 90 dB
62 Hz 16 msec 32 msec 0.59
μ
a
470 Hz 2 msec 4 msec 2.27
μ
a