Lenze 8400 TopLine - Manual (Page 356)

6 Encoder/feedback system
6.4 Frequency HTL encoder (DI1/DI2, DI6/DI7)
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Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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Tip!
• We recommend to use the preset combined encoder method ( C00496 = 2).
• Use one of the first three procedures ( C00496 = 0, 1, or 2) for dynamic applications (e.g.
operating mode: servo control).
• For dynamic speed control or positioning processes, use an HTL encoder with 1024
increments.
Low speeds (except for edge counting)
For the first three methods (
C00496 = 0, 1, or 2), the minimum speed that can be measured depends
on the encoder resolution.
The quantisation error
• is independent of the encoder resolution,
• exclusively depends on the encoder quality (encoder errors).
• at least amounts to 0.5 rpm.
Internal arithmetic operations automatically maintain the minimally required value of the scanning
time in order to achieve maximum dynamics.
Low speeds with edge counting
The minimum speed that can be measured and the quantisation error of speed measurement in the
edge-counting procedure ( C00496 = 3) depend on the scanning time that can be set in C00425/1
and the encoder resolution.
Depending on accuracy and the requirements with regard to the dynamic performance, the
respective scanning time must be selected and set in C00425/1 :
Encoder
resolution
(Number of
increments)
Min. measurable speed in [rpm]
8 16
16 8
32 4
64 2
128 1
256 0.5
≥ 512 0.25
Encoder
resolution
(Number of
increments)
Scanning time [ms]
1 2 5 10 20 50 100 200 500 1000
Min. measurable speed in [rpm]
8 1875 938 375 188 93.8 37.5 18.8 9.4 3.8 1.9
16 938 469 188 94 46.9 18.8 9.4 4.7 1.9 0.9
32 469 234 94 46.9 23.4 9.4 4.7 2.3 0.9 0.5
64 234 117 46.9 23.4 11.7 4.7 2.3 1.2 0.5 0.2
128 117 58.6 23.4 11.7 5.9 2.3 1.2 0.6 0.2 0.12
256 58.6 29.3 11.7 5.9 2.9 1.2 0.6 0.3 0.12 0.06
512 29.3 14.6 5.9 2.9 1.5 0.6 0.3 0.15 0.06 0.03
1024 14.6 7.3 2.9 1.5 0.7 0.3 0.15 0.07 0.03 0.01