Absolute rotary encoder P**58
Encoder classes of the PROFIBUS user organisation
Subject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
Pepperl+Fuchs Group • Tel.: Germany +49 621 776-0 • USA +1 330 4253555 • Singapore +65 67799091 • Internet http://www.pepperl-fuchs.com
Date of issue 01/15/04
15
4.1.6 Overall resolution
The "Overall resolution" parameter allows users to adjust the measurement range of
the device: The rotary encoder increments up to the overall resolution assigned by
parameter and then starts again at 0.
Example: If 100 steps have been selected per revolution with an overall resolution of
12,800, the rotary encoder starts again at zero after 128 revolutions and then counts
up to 11,799 again.
For many projecting tools, the value must be divided up into high word and low word;
for more information see also section 7.4, page 34
When entering the "Overall resolution" parameter, note also the following:
4.2 Data exchange in normal operation
The so-called DDLM_Data_Exchange mode is the normal state of operation for the
system. On request, the rotary encoder sends current (position) values to the master.
Vice versa, the rotary encoder is also capable of receiving cyclic data (for example
the preset value for a Class 2 encoder).
Selected overall resolution in measurement steps
Octet 14 15 16 17
Bit 31 ... 24 23 ... 16 15 ... 8 7 ... 0
Data
2
31
to 2
24
2
23
to 2
16
2
15
to 2
8
2
7
to 2
0
If n steps have been selected per revolution, the overall resolution that
is selected must not result in the period being longer than the
maximum available (physical) number of revolutions of the device (see
manufacturer's rating plate), i. e. for a Multiturn device running at
16,384 revolutions, the device resolution must be less than 16,384
times the number of steps per revolution set by parameter:
Overall resolution < measurement steps per revolution x number
of revolutions (physical)
If this is not taken into consideration, the device indicates a parameter
error and does not switch into cyclic data exchange.
The period and thus the overall resolution/measurement steps per
revolution must be an integer number. In addition, when 16,384 is
divided by it, the result must be an even number (integer division with
no remainder). The following expression must thus be true:
(16,384 x measurement steps per revolution)/overall resolution =
integer number
Note
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