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FAQ

How to check the right mounting of the EES37 / EEM37?

Article No: KA-02722
Version: 1.2
Subject to change without notice
The possibility to read out the rotor position
Related Products
EES/EEM37
motor feedback systems

Table of Contents

The EES37 / EEM37 has an additional function compared to the SEy37. It is possible to check the axial position of the rotor, when the encoder is mounted in the motor.

For this functionality, the encoder doesn't need an additional sensor. The encoder is able to generate this with the capacitive sensing unit. It is analyzing the vector length of the raw values to get feedback about the position of the rotor between the capacitor plates.

 

The distance between the 2 capacitor plates is 3.15 mm. The thickness of the rotor is 1.4 mm. Thus, the mechanical moving space of the rotor between the capacitor plates is 1.75 mm.

In the data sheet, you find the permissible shaft movement, which is +- 0.5 mm. Then there is a rest space of 0.35 mm each side, until the rotor touches the capacitor plates.

 

With a long message, it is possible to read out the current rotor position (RID: 0D4h, indirect, length: 2 byte).

The result of this request is:

  • 00 02 hex (2) = rotor position in +Z axis is critical ? approx. >0.4mm
  • 00 01 hex (1) = rotor position in +Z axis tolerable ? approx. 0.2mm .. 0.4mm
  • 00 00 hex (0) = rotor position in Z axis ideal ? approx 0.2mm .. -0.2mm
  • FF FF hex (65535 / -1) = rotor position in -Z axis tolerable ? approx. -0.2mm .. -0.4mm
  • FF FE hex (65534 / -2) = rotor position in -Z axis is critical ? <-0.4mm

If the rotor is out of range, ">0.5mm or <-0.5mm", the encoder generates an error message.
This means, the encoder detects usually a wrong mounting, after the encoder was removed from the motor.

The error is in the error register 43h the Bit 1,  critical rotor position.
Keywords:
ees37, eem37, right mounting, additional function, axis position, check the right mounting, axial mounting, motor feedback
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