Siemens SINUMERIK 840C - Manual (Page 857)

12 Functional Descriptions 04.96
12.11.2 ENDAT absolute encoder (SW 5.2 and higher)
12.11.2.2 Hardware requirements
The ENDAT absolute encoder can only be used in conjunction with the new digital
SIMODRIVE 611D modules ”Standard and performance”.
Order No.: 6SN1118-0DM13-0AA0 2-axis version (Standard)
Order No.: 6SN1118-0DG23-0AA0 1-axis version (Performance)
Order No.: 6SN1118-0DH23-0AA0 2-axis version (Performance)
The necessary software is available as from NC software version 5.2.
12.11.2.3 Accuracy
Relevant measuring system data
• Grid spacing:
The size of the grid spacing (=size of the pitch period of the finest track) is taken from the
company data sheet for the EnDat encoder.
• EnDat measuring step:
The EnDat measuring step (effectively the same as the EnDat encoder resolution) is taken
from the company data sheet for the EnDat encoder.
• Incremental measuring step:
The incremental measuring step (= measuring system resolution with which the NC
position control is working) results from the interaction between incremental encoder and
interpolating evaluation electronics (HW + SW).
Incremental measuring step = grid spacing/product of all pulse multiplications).
• NC-MD 1264* (grid spacing/EnDat measuring step):
The NC requires this MD to convert the EnDat measuring steps into incremental
measuring steps. Only input values which are integer and can be divided by 4 are
processed by the control. With this MD, the default value = 0 for the encoder EQN 1325
is correct, i.e. it is internally interpreted as value 4. In the list display: User displays/NC
data/Axis/Measuring system data, this MD is entered directly after MD 1808*, bit 6.
Example EQN 1325:
Spindle pitch 10 mm
No. of encoder markings, finest track 2048
Internal pulse multiplication 4
External pulse multiplication (interpolation) 512
Position controller resolution 0.5 *10 -3 mm, (0.5 µ m)
Rotary grid spacing= = 0.000488 rev.
1 revolution
2048
Linear grid spacing= = 4.88 µ m
2048
10 mm
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SINUMERIK 840C (IA)