26
.9.20
1
3
78
AS-i 3.0 PROFIBUS Gateway in Stainless Steel
Appendix: Example for startup on a Siemens S7
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.
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 occu-
py bits 7 - 4 in I/O byte 8 of the controller.
Assignment of the I/O address and AS-i slave address
Address byte
Bits 7 - 4
Bits 3 - 0
I/O byte 2
flags
slave 1
I/O byte 3
slave 2
slave 3
I/O byte 4
slave 4
slave 5
I/O byte 5
slave 6
slave 7
I/O byte 6
slave 8
slave 9
I/O byte 7
slave 10
slave 11
I/O byte 8
slave 12
slave 13
I/O byte 9
slave 14
slave 15
I/O byte 10
slave 16
slave 17
I/O byte 11
slave 18
slave 19
I/O byte 12
slave 20
slave 21
I/O byte 13
slave 22
slave 23
I/O byte 14
slave 24
slave 25
I/O byte 15
slave 26
slave 27
I/O byte 16
slave 28
slave 29
I/O byte 17
slave 30
slave 31
Tab. 12-29.
