Lenze 8400 motec - Manual (Page 161)

Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05 161
5 Motor control (MCTRL)
5.11 Encoder/feedback system
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5.11.1 Encoder evaluation method
Depending on the encoder used, the following table specifies which evaluation method should be
selected in C00496 :

Tip!
We recommend the use of the preset procedure for low-resolution encoders (
C00496 = 1).
Low speeds during evaluation procedure for low-resolution encoders
When the evaluation procedure for low-resolution encoders (
C00496 = 1) is used, the minimally
measurable speed depends on the number of increments of the encoder.
The quantisation error
• is independent of the encoder increment,
• exclusively depends on the encoder quality (encoder errors).
• amounts to at least 0.5 rpm.
Internal arithmetic operations automatically maintain the minimally required value of the scanning
time in order to achieve maximum dynamics.
Selection in C00496 Encoder evaluation method
1: Low-resolution encoder
(Lenze setting)
High-precision procedure for low-resolution encoders (<=128 increments)
• Exact method for speed measurement with automatic scanning time setting
(0.5 … 500 ms) for low-resolution encoders in the range of 4 …. 128 increments.
• Evaluation with automatic scanning time minimisation for an optimum dynamic
performance.
• Method is also suited for encoders with poor signal quality, e.g. for encoders with
high error rate in scanning ratio and phase offset.
• This method requires an equidistant period length per encoder increment.
• Wiring according to EMC (e.g. motor and encoder cable shielding) is required!
3: Edge-counting procedure Simple edge counting procedure with adjustable scanning time ( C00425 )
• Speed measurement by means of the edges of tracks A and B measured per
scanning interval.
• Integrated correction algorithm for EMC interference.
• Limited suitability for systems with unshielded encoder and/or motor cable.
• Limited suitability for encoders with poor signal quality, i.e. high error rate in
scanning ratio and phase offset.
Number of encoder increments C00420/1 Minimum speed [rpm]
8 16
16 8
32 4
64 2
128 1
256 0.5