Siemens SINUMERIK 840Di sl - Message Format for Cyclic DP Communication

PROFIBUS DP Communication
8.1 General information
Manual
Commissioning Manual, 05/2008, 6FC5397–4CP10–4BA0
231
8.1.3 Message format for cyclic DP communication
Message frame structure
A PROFIBUS message generally adopts the following format for cyclic data transmission:
8VHIXOGDWD332
3DUDPHWHULGHQWLILHUYDOXH
3.:
3URFHVVGDWD
3='
3URWRFRO
IUDPH
7UDLOHU
3URWRFRO
IUDPH
+HDGHU
Figure 8-1 Main message format for cyclic data transmission
User data structure
The useful data for cyclic communication are referred to as parameter process data objects
(PPO). They are subdivided into two areas within the message frame:
● Parameter area (PIV, parameter identification value)
This telegram section is used to read and/or write parameters and to read out faults.
● Process data area (PDA, process data)
In the case of a drive, for example, this area contains the control words, setpoints, or
additional information and actual values.
The following data are transmitted with the process data:
– Control words and setpoints (task: Master --> Drive) or
– Status words and actual values (responses: Drive --> Master)