How The Interfaces Work - Siemens DP/AS-Interface Link 20E Manual

2.2

How the Interfaces Work

Accessing the AS-Interface via PROFIBUS DP
The DP master communicates with the AS-i slaves via the DP/AS-i Link 20E. The
AS-i communication objects are mapped in one continuous data area for input data
and one for output data in the DP master.
Due to its function, the DP/AS-i Link 20E must operate two interfaces:
Interface to the DP master : PROFIBUS-DP
1.
Interface to the AS-i slaves :
2.
DP master
Cyclic services
Write binary values
Read binary values
Acyclic services
write_record
S
Write analog values
S
Command job
read_record
S
Analog values
S
Command response
Interface to DP master : PROFIBUS-DP
At the PROFIBUS end, the cyclic services and the acyclic services of
PROFIBUS-DP V1 are used:
S Cyclic services
The cyclic services are used to transfer binary values.
S Acyclic services of PROFIBUS-DP V1
In the remainder of this description, these services are known as read_record
and write_record. They are used for the following:
– The transfer of analog values
– To operate the command interface
DP/AS-Interface Link 20E
Release 11/2002
C79000-G8976-C138–04
Data Exchange Between the DP Master and AS-i Slave
AS-Interface
DP/AS-i Link
29 24 19 14
28 23
18 13
22
27 17 12
31 26 21 16 11
30 25 20 15 10
PROFIBUS
Í Í Í
Í Í Í Î Î
ADR Í Í Í
DP-AS Interface
BF
Link 20
DIA
9 4 SF
8 3 APF
7 2 CER Í Í Í
6 1 AUP
X 2
3 4
5 0 CM
6GK7 1415 2AA0
Í Í Í Í Í Í
Í Í Í Î Î
Î Î Î
Î Î Î
Î Î Î Í Í Í
Î Î Î Í Í Í
Î Î Î
AS-Interface
AS-i slaves
AS-i
slave 1
AS-i
slave 2
Î Î
AS-i
slave n
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