Message Frame Structure For Cyclic Dp Communication - Siemens SINUMERIK 840Di Manual

7 PROFIBUS DP Communication
7.1 General
7.1.1

Message frame structure for cyclic DP communication

Message frame
structure
Useful data
structure
7-204
This is the message frame structure for cyclic DP communication using the
drive "SIMODRIVE 611 universal".
The message frames for cycle data transmission have the following basic struc-
ture:
Drive A
Useful data (PPO)
Protocol
frame
Parameter
identifier
(header)
value
(PIV)
Note:
The useful data for drive B are only transmitted when "DP slave 611U" is
operated as a double-axis module.
Fig. 7-1 Message frame structure for cyclic data transmission
The useful data for cyclic operation are termed parameter process data objects
(PPO). The are subdivided into two areas within the message frame:
S
Parameter area (PIV, parameter identifier value)
This part of the message frame is for reading and/or writing parameters and
for reading out faults.
S
Process data area (PDA, process data)
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 (requests: master ––> drive) or
– status words and actual values (responses: drive ––> master).
Drive B
Useful data (PPO)
Process Parameter
data identifier
(PDA) value
(PIV)
 Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
06.03
Protocol
frame
Process
data
(trailer)
(PDA)