6encoder/feedback system – Lenze 8400 TopLine User Manual
Page 340
6
Encoder/feedback system
6.3
Multi-Encoder (X8)
340
Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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SSI encoder coding "Position Gray"
From version 14.00.00 onwards
, also SSI encoders are supported that transfer the position data in
Gray coding and the status bit in binary mode (uncoded). For an encoder with this coding, select
"2:Position Gray" in
. Then, only the pure position data are converted from Gray to binary
code, and status bits provided by the encoder are directly evaluated. The position data converted to
binary format are then added to the status bits again and provided as raw value at the outputs
wHighWord and wLowWord of the
. This takes place as a provision of the position
raw value in gray code would not make any sense; the value, in case of a linear encoder, would
feature jumps instead of a linear characteristic.
Evaluation of further status bits
From version 14.00.00 onwards
, two more status bits of the SSI encoder can be evaluated. The bits
to be evaluated in the SSI data current have to be set in
.
If the evaluation of a status bit shall be deactivated completely, the value "32" has to be entered into
the corresponding code. Thus, the status bit always has the value "0".
Left shift of raw value
The data read-in by the encoder is processed via the settings of the start bits for singleturn and
multiturn and the number of bits in such a way that a position signal suitable for the controller is
created that can be fed into the function block interconnection.
The raw value of the received data coming from the SSI encoder is provided at the outputs
. It is always provided in binary format, i.e. in
case of Gray code encoders after the received data is decoded. The MSB of the data is positioned at
bit 16 of the wHighWord output.
In order to receive a standard data format (LSB at the lowest position) an offset can be set in
= 32 - data word length serves to display the raw value of the
received data telegram so that the LSB is at bit 0 of the wLowWord output:
Clarification of the data sequence when the data word length is = 26 bits
wHighWord
wLowWord
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
Data sequence without offset (
= 0):
25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
Data sequence with an offset by 6 bits (
= 6):
25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0