Siemens SINUMERIK 840C Installation Instructions Manual page 736

10 Axis and Spindle Installation
10.4.5 Distance-coded reference marks
3. Direction of linear scale as compared with the machine system
It should be made clear how the linear scale is applied to the machine system. Whether the
direction is positive or negative is defined in MD 1808*.
• NC MD 1808*, bit 2 = 0
• NC MD 1808*, bit 2 = 1
4. Determining the offset of (linear) scale and machine system
(Absolute offset)
Structure of the linear scale with coded reference marks:
1 2
.
(a/2+1) k
a .
with n =
Using the above example:
1 2
10.02
20
10–46
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Linear scale same direction as machine system
Linear scale opposite direction to machine system
3 4 5
. . .
(a/2-1) k (a/2+2) k (a/2-2) k (a/2+3)
k a . k
(
n-1)
Measured length on scale
.
a k
3 4 5
9.98 10.04 9.96 10.06
20
.
(n-1) 20
ManualsBase.com
6 7
. .
k (a/2-3) k
a . k
. .
a k
6 7
9.94
20
© Siemens AG 1992 All Rights Reserved
11.92
k
X min
(a/2
.
.
(a/2+n) k
-n) k
a . k
Reference mark
k
X min
10-n
10+n 0.02
0.02
20
Reference mark
6FC5197- AA50
SINUMERIK 840C (IA)