Siemens DP/AS-Interface Link 20E

Data Exchange Between the DP Master and AS-i Slave
47
DP/AS-Interface Link 20E
Release 11/2002
C79000-G8976-C138–04
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:
1. Interface to the DP master : PROFIBUS-DP
2. Interface to the AS-i slaves : AS-Interface
DP master
AS-i
slave 2
AS-i
slave 1
AS-i
slave n
ÍÍÍ
ÍÍÍ
ÍÍÍ
ÎÎÎ
ÎÎÎ
ÎÎÎ
AS-i slaves
ÍÍÍ
ÍÍÍ
ÎÎ
ÍÍÍ
ÍÍÍ
ÎÎ
ÎÎ
ÍÍÍ
ÍÍÍ
ÎÎÎ
ÎÎÎ
PROFIBUS AS-Interface
DP/AS-i Link
Cyclic services
read_record
S Analog values
S Command response
write_record
S Write analog values
S Command job
Write binary values
Acyclic services
SF
APF
CER
AUP
CM
6GK7 1415 2AA0
1
2
3
4
5
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8
0
9
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20
21
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23
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X 2
3 4
DIA
ADR
BF
DP-AS Interface
Link 20
Read binary values
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