Lenze E94AYFLF Digital frequency module - Manual (Page 17)

EDS94AYFLF EN 3.2 - 10/2010
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Digital frequency extension module | Parameter setting & configuration
Digital frequency input
Problem description - speed variations
2.3 Problem description - speed variations
In the digital frequency extension module rectangular encoder signals are processed. The
speed is determined by counting the edges occurring within a defined time interval (1 ms).
Due to this defined time interval of 1 ms and a finite number of encoder increments per
revolution, the calculated speed signal can only assume discrete values. This gives the
impression that the signal is very unsteady and inexact. This effect increases with lower
numbers of increments.
An example for calculating the expected speed variation can be found in chapter "Digital
frequency output".  Problem description - speed variations
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