Lenze E94AxPExxxx - Manual (Page 301)

Lenze · 9400 Servo PLC· Reference manual · DMS 4.0 EN · 11/2013 · TD05/06
301
7 Encoder evaluation
7.3 Parameter setting
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7.3.9 Rotative encoder with SSI protocol
In accordance with the parameterisation of the system block LS_SsiEncoderX8, the position
information of the encoder is available in a partword and only has to be sent to the position
controller via the SB LS_Feedback.
In accordance with the Lenze setting of the position encoder gearbox factor (
C02522 = 1,
C02523 1 = 1), it is expected that one encoder revolution corresponds to one rotation at the output
end, i.e. to a feed rate in accordance with the feed constant C02524 .
The position information from the SSI data word is converted to the internal scale with the function
block L_EsEnconderConv, with which a certain machine position can be set as the reference/starting
position. The parameterisation of the block makes it possible for the position to be reconstructed
after mains switching. This is necessary if the absolute encoder display range of e.g. 4096
revolutions has been left.
Example: Material feed with length measurement by means of measuring wheel and SSI encoder
The current position of the material of a feed unit is detected with a rotative SSI encoder. One
encoder revolution corresponds to one revolution of the measuring wheel (400 mm).
Every time the slip-free drive roll revolves, the material is moved 1200 mm in an axial direction. The
current motor speed is detected by a resolver.
The lower 24 bits of the SSI data word contain the position information coded in Gray. The SSI
encoder supplies 4096 gradations per revolution and has an absolute display range of 4096
revolutions.
[7-12] Schematic diagram of feedback with laser distance measuring device DME5000
Required FB interconnection
 Motor encoder
 SSI encoder
 Circumference of the measuring wheel = 400 mm
 Circumference of the drive roll = 848,23 mm
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