Chapter 1 Basics
Manual VIPA Accessories
1-10
HB37E - IM - RE_306-1LE00 - Rev. 09/28
When addressing data, Profibus assumes that the physical structure of the
slaves is
modular
or it can be structured internally in logical functional units,
so-called
modules
. This model is also used in the basic DP functions for
cyclic data communication where each module has a constant number of
input-/output bytes that are transmitted in a fixed position in the user data
telegram. The addressing procedure is based on identifiers, which
characterize a module type as input, output or a combination of both. All
identifiers combined produce the
configuration
of the slave, which is also
checked by the DPM when the system starts up.
The acyclic data communication is also based on this model. All data
blocks enabled for read/write access are also regarded as assigned to the
modules and can be addressed using slot number and index.
The
Slot_Number
addresses the module and the
index
addresses the data
blocks of a module. The Slot_Number = 0 addresses data of the Profibus
coupler, Slot_Number > 0 addresses the data of the function modules.
0
1
2
3
5
Slot_Number
Data structure
2Byte Output
(Modul 1)
2Byte Output
(Modul 2)
2Byte Input
(Modul 3)
4Byte Input
(Modul 4)
Request:
Response:
...
...
...
...
I/O
Module 1
Index
0 - 255
I/O
Module 2
Index
0 - 255
I/O
Module 3
Index
0 - 255
I/O
Module 4
Index
0 - 255
I/O
Module 5
Index
0 - 255
Slave
Index
0 - 255
4
Each data block can be up to 244bytes. In the case of modular devices, the
slot number is assigned to the modules. Compact devices are regarded as
a unit of virtual modules. These can also be addressed whit slot number
and index. Through the length specification in the read/write request, it is
also possible to read/write parts of a data block.
Note!
For the addressing at the deployment of the Siemens SIMATIC manager
the following conventions are valid:
DP slave coupler: Setting of the
diagnostic address
as ID.
Modules of the DP slave coupler: Setting of the
module address
as ID. For
an output module you have to set additionally bit 15 of the module address
(e.g. address 0004h becomes 8004h). With a combination module you
have to set the lower one of the two addresses.
Addressing with
Slot and Index