Rockwell Automation Allen-Bradley 1794-IJ2, Installation Instructions Manual

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Rockwell Automation Publication 1794-IN049E-EN-P - May 2022 7
FLEX I/O 2-input Frequency Modules Installation Instructions
Resolution and Accuracy
+1 Hz or +0.1 Hz (depending on frequency range bit setting), or + accuracy specification listed in Table 1 , whichever is greater.
Table 1 - Accuracy Specifications
Accuracy
Min. Freq. Sample
Time (ms) Sampling Accuracy Time Base Accuracy Worst Case Total
Accuracy
Deviation in Hz Due to Total Accuracy
Resolution
1.0…3276.7 Freq. Range
(in Hz)
1…32767 Freq. Range
(in Hz)
2 +0.02% +0.0225% +0.0425 +0.1…1.4 +1…14 0.01%
4 +0.01% +0.0225% +0.0325 +0.1…1.1 +1…11 0.005%
5 +0.008% +0.0225% +0.0305 +0.1…1.0 +1…10 0.004%
10 +0.004% +0.0225% +0.0265 +0.1…0.9 +1…9 0.002%
20 +0.002% +0.0225% +0.0245 +0.1…0.8 +1…8 0.001%
50 +0.0008% +0.0225% +0.0233 +0.1…0.8 +1…8 0.0004%
100 +0.0004% +0.0225% +0.0229 +0.1…0.8 +1…8 0.0002%
200 +0.0002% +0.0225% +0.0227 +0.1…0.7 +1…7 0.0001%
500 +0.00008% +0.0225% +0.02258 +0.1…0.7 +1…7 0.00004%
1000 +0.00004% +0.0225% +0.02254 +0.1…0.7 +1…7 0.00002%
Table 2 - Input Map
Bit

15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Word  Read
0 Frequency 0…32,767 or 0.0…3,276.7 Channel 0
1 % Full Scale 0.0
…
3,276.7% Channel 0 or Acceleration -32,768
…
32,767 Channel 0
2 Frequency 0
…
32,767 or 0.0
…
3,276.7 Channel 1
3 % Full Scale 0.0
…
3,276.7% Channel 1 or Acceleration -32,768
…
32,767 Channel 1
4 R R Direction CH 0
GS
CH 0
F/A CH 0 WO CH 0 MPA CH 0 R R Direction CH 1
GS
CH 1
F/A CH 1 WO CH 1 MPA CH 1
5 Reserved
Diagnostic Status
Channel 0
Reserved
Diagnostic Status
Channel 1
6 Reserved
Where:
GS = Gate state
F/A = Frequency/Accel alarm
WO = Wire-off alarm
MPA = Missing pulse alarm
R = Reserved
2
Minimum frequency sample time
% Resolution =
count frequency x minimum frequency sample time
Accuracy % is defined as:
Resolution % is defined as:
% Accuracy = 100
count frequency
1
100
Minimum frequency
sample time
2
1 -
+