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In the structure of the 16-byte I/O data field each AS-i slave has a 4-bit data field.
This is determined by the address of the AS-i slave within the AS-i circuit.
Address byte
I/O byte 2
I/O byte 3
I/O byte 4
I/O byte 5
I/O byte 6
I/O byte 7
I/O byte 8
I/O byte 9
I/O byte 10
I/O byte 11
I/O byte 12
I/O byte 13
I/O byte 14
I/O byte 15
I/O byte 16
I/O byte 17
The data for the slaves present and projected in the AS-i circuit are refreshed
based on their position in the I/O data field.
The data fields for non-present slaves are filled with zero.
This means for example the AS-i data for the AS-i slave having Address 12 occupy
bits 7 - 4 in I/O byte 8 of the controller.
Subject to reasonable modifications due to technical advances.
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Appendix: Example for startup on a Siemens S7
Assignment of the I/O address and AS-i slave address
Bits 7 - 4
flags
slave 2
slave 4
slave 6
slave 8
slave 10
slave 12
slave 14
slave 16
slave 18
slave 20
slave 22
slave 24
slave 26
slave 28
slave 30
AS-Interface
Bits 3 - 0
slave 1
slave 3
slave 5
slave 7
slave 9
slave 11
slave 13
slave 15
slave 17
slave 19
slave 21
slave 23
slave 25
slave 27
slave 29
slave 31
Copyright Pepperl+Fuchs, Printed in Germany
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