Rockwell Automation 1769-HSC Compact High Speed Counter Module - Manual (Page 127)

Rockwell Automation Publication 1769-UM006E-EN-P - July 2013 127
Specifications Appendix A
Rate Accuracy The following graph shows rate error at various frequencies. The following trends
can assist you in reading the graph:
• Of the lines that rise at low frequencies, the left-most is a 10-second update
time (Ctr
nCyclicRateUpdateTime = 10000).
• The right-most of these lines is a 1-millisecond update time
(Ctr
nCyclicRateUpdateTime = 1).
• The line that rises at high frequencies illustrates Ctr[ n].PulseInterval.
Figure 21 - Rate Errors Comparison
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
10 100 1,000 10,000 100,000 1,000,0
1
5
10
50
100
500
1000
10000
CPI
Frequency (Hz)
Error
(Percent)