JVL MIS17 Series, User Manual

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122 JVL Industri Elektronik A/S - User Manual - Integrated Stepper Motors MIS17x, 23x, 34x, 43x
5.8 Absolute Multi-turn Encoder
5.8.1 Introduction
Optional the MIS motors can be equipped with the absolute multi-turn encoder (MISxxx-
zzyy H3/H4 nn option) which offers the possibility to keep track of the position regardless
if power is connected or not.
When this option is present a mechanical zero search is only necessary one time after
installation and the system will keep track of the actual motor position at any time after-
wards.
The encoder is based on a magnetic principle which do not offer the same resolution and
precision as the more expensive optical based solutions. It do however offer the advan-
tage to keep track of the position without power applied. The magnet principle is also
much more tolerant to mechanical stress such as shock and extreme temperatures.
The absolute multi-turn option offers the following main features.
Encoder:
Resolution 409.600 counts per revolution displayed (internal 1024 cpr)
Accuracy +/- 0,1% of full scale
Repeatability +/- 0,1% of full scale
Position range ±5242 motor revolutions (+/- 2^31 motor counts)
Motor:
Resolution 409.600 counts per revolution (standard)
As seen above the motor resolution is much higher than the encoder resolution. The en-
coder option is however mostly used for stall detection at the motor (the motor loose
its position) and for this situation the encoder will be adequate since the motor can only
stall in multiples of a 1/50 shaft revolution corresponding to 7.2 mechanical degrees.
Only MISxxx--- H3/H4 --