Command Interface; Construction - Pepperl+Fuchs VBG-PB-K25 Manual

8

Command Interface

8.1

Construction

If an AS-i slave is addressed in a command or in a response, the address is struc-
tured as shown below
byte
1
2
3
...
36
byte
1
2
3
...
36
Command byte and T-bit are always part of the response. The T-bit is necessary
to operate the command interface via a MSC1 connection (PROFIBUS DP V0).
This way the same command of the command interface can be used two twice re-
peatedly, possibly with different parameters.
The execution of a command of the command interface is declined, if the number
of the transferred parameters is too small which means that the command inter-
face in the cyclic channel is too small or the DP V1-telegram is too short.
The commands of the command interface are valid as well for PROFIBUS DP V0
as for PROFIBUS DP V1.Circuit = 0If an AS-i gateway with one AS-i master or the
master 1 of an AS-i
Circuit = 1
The commands for reading and writinig exist in two variations. At the first variation
the bits in the slave lists are arranged as usually with Pepperl+Fuchs products:
Data for slave with lower address appear in the lower bits. The second variation is
compatible to Siemens masters: The sequence of the bits in the slave lists bytes
are inverse.
Switching between the two variations can be done with bit 2
quest. If it is deleted, the Pepperl+Fuchs arrangement is selected, otherwise the
Siemens compatible arrangement is selected.
Subject to reasonable modifications due to technical advances.
28
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7 6 5
2 2 2
T –
request parameter byte 34
7 6 5
2 2 2
T
response parameter byte 1
response parameter byte 34
gateway with 2 masters should be choosen.
If master 2 of a double master should be chosen.
Request
4 3
2 2
command
circuit
request parameter byte 1
...
Response
4 3
2 2
command
result
...
AS-Interface
Command Interface
2 1
2 2
2 1
2 2
6
in byte 2 of the re-
Copyright Pepperl+Fuchs, Printed in Germany
0
2
0
2