HEIDENHAIN PWM 20 - Manual (Page 177)

180 HEIDENHAIN ATS Software User's Manual
Example:
Inspection of a linear encoder with distance-coded reference marks (LS 187C)
Schematic representation of an incremental graduation with distance-coded reference marks
(For more information on reference marks, see product catalogs.)
In the next illustration, the counting function was started at the beginning of the measuring
length of the LS (ID label).
The Reference table shows the signal periods measured between two reference marks.
Example:
501 + 499 = 1000
The RM nominal increment of the LC 187C is 1000 signal periods.
Signal period: 20 µm
Nominal increment/base (
G ): 1000 signal periods (= 20 mm traverse path max.)
First encoded distance = 10.02 mm, i.e. 501 signal periods (10.02 / 20
 1000)
Second encoded distance = 9.98 mm, i.e. 499 signal periods (9.98 / 20
 1000)
Third encoded distance = 10.04 mm,i.e. 502 signal periods (10.04 / 20
 1000)
Fourth encoded distance = 9.96 mm, i.e. 498 signal periods, etc.
The distance-coded reference mark can be checked in the Counter table.
In this table, the nominal increment is referred to as "base".
Note
To calculate the nominal increment (base) the software requires 6 reference marks (single-
column table).
As soon as the nominal increment has been determined, the table shows three columns (the
table and the graphics were cleared before).
Now you can move the scanning unit back to the beginning of measurement.
If you move the scanning unit away from the ID label, the first line of the table contains the
value 1: 501, the value 2: 499 and the base 1000, etc. (see figure).