Machine Data For The Encoder - Siemens SIMATIC FM 351 Installation Manual

8.5

Machine Data for the Encoder

Definition
The encoder supplies the displacement information to the module which
evaluates it and converts to an actual value using the resolution.
It is only by correctly specifying the machine data of the encoder that you
can ensure that the determined actual value of the axis position matches the
real axis position.
Data List The following table describes all the data which you can parameterize in the
Encoder dialog field on the parameterization interface.
Table 8-4

Machine Data for the Encoder

Machine Data and
Assignment
Encoder type: You will find information about the working principle of encoders
5 V incremental
24 V incremental
Absolute (SSI)
Frame length The machine data is only present with an absolute encoder.
13 bit With the frame length you define the behavior of the FM 351 on receiving the encoder
signal. You define the cycle frame which the FM 351 outputs.
25 bit
Displacement per encoder With the machine data "Displacement per encoder revolution" you inform the FM 351
revolution: of the distance covered by the drive system per encoder revolution.
1 to 1,000,000.000 mm The value Displacement per encoder revolution depends on how your axis is set up
and the position of the encoder. With this value you must take into account all trans-
mission components such as couplings or gear units (take note of the illustrations in
this table).
If you do not take into account all the transmission components, the determined resolu-
tion does not represent the resolution of the table or of the tool.
Please take note also of Chapter 8.6 (Resolution). It describes the relationship between
the machine data Displacement per encoder revolution and Increments per encoder
revolution.
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
In this manual
– You will find information of a general nature about encoder systems in Chap-
ter 10 (Encoders).
– You will find special information on the connection of the encoders in Chapter
4.2 (Connecting the Encoders).
In the relevant data sheets.
Motor
Encoder
Gear unit
Motor
Gear unit
Machine Data and Increments
Description
Encoder
8
8-13