Acces s ing data v ia PRO F I BUS
Operating manual for PROFIBUS fieldbus | DOC01185928-0008 | 2016-12 | V1.8 DE
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4.3.1
Non-cyclic data
PROFIBUS principally has a slot and an address when accessing non-cyclical data. Both are 8 bit
values.
The index covers the number range from 0 – 255.
The slot supports the values 0, 1 and 2.
The addressing of the non-cyclical data can be carried out in 2 different ways.
4.3.2
Direct access
Slots 1 and 2 are used for direct access.
The number of the parameter to be read or written is composed of the slot number and the
transmitted index of the non-cyclical access.
Slot no. 1 addresses the parameters 0 – 255 through the index.
Slot no. 2 addresses the parameters 256 – 511 through the index.
INFORMATION
The Siemens S7 PROFIBUS master offers the functional components SFB 52 and SFB 53 for
direct access.
The slot number is addressed by the parameter ID of the SFBs.
The INDEX is addressed by the parameter INDEX of the SFBs.
Slot
Index
Parameter
1
0
0
1
1
1
1
•
•
1
•
•
1
254
254
1
255
255
Slot
Index
Parameter
2
0
256
2
1
257
2
•
•
2
•
•
2
254
510
2
255
511