Siemens SINUMERIK 840Di, Руководство пользователя

Страница: 204 / 552

06.03
7.1 General
7-204

Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
7.1.1 Message frame structure for cyclic DP communication
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:
Useful data (PPO)
Parameter
identifier
value
(PIV) Process
data
(PDA)
Useful data (PPO)
Parameter
identifier
value
(PIV) Process
data
(PDA)
Protocol
frame
(trailer)
Drive A Drive B
Note:
The useful data for drive B are only transmitted when “DP slave 611U” is
operated as a double-axis module.
Protocol
frame
(header)
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).
Message frame
structure
Useful data
structure
7 PROFIBUS DP Communication