5
5.2
Basic functions of the cyclic data transfer
5-206
Siemens AG 2005 All Rights Reserved
SIMODRIVE 611 universal Description of Functions (FBU) – 04.05 Edition
5.2
Basic functions of the cyclic data transfer
The structure of the net data for cyclic operation, is designated as para-
meter–process data–object (PPO) in the ”PROFIBUS profile, variable–
speed drives”.
The net data structure for cyclic data transfer is sub–divided into two
areas, which are transferred in each telegram.
Parameter area (PKW, parameter identification value)
This telegram section is used to read and/or write parameters and
to read out faults. The data transfer is optional and can be defined
by appropriately configuring the system.
The mechanisms, used to apply the PKW part, are described in
Chapter 5.6.7.
Process data area (PZD, process data)
This area contains the control words, setpoints and status informa-
tion and actual values.
The following data is transferred with the process data:
– Control words and setpoints (task: master ––> drive) and
– Status words and actual values (responses: drive ––> master)
When the bus system is commissioned, the master defines which PPO
type is used to address a drive. The ”DP slave 611U” is automatically
signaled the selected PPO–TYPE at run–up via the configuration tele-
gram.
With cyclic data transfer, setpoints and actual values are transferred
one after the other between the master and its associated slaves in a
cycle.
For standard DP operation, a new cycle is started after the old cycle
has been completed.
For clock–synchronous operation, a new cycle is started with the se-
lected T
DP
clock cycle.
The telegrams of the cyclic data transfer have, in both cases, the fol-
lowing basic structure:
Net data (PPO)
Parameter
ID
value
(PKW)
1)
Process
data
(PZD)
Net data (PPO)
Parameter
ID
value
(PKW)
1)
Process
data
(PZD)
Protocol
frame
(trailer)
Drive A
Drive B
Note:
Net data for drive B is only transferred, if the ”DP slave 611U” operates as
double–axis module.
––> refer to Chapter 5.9 under P0875
1) Transfer is optional and is defined by appropriately configuring the system.
Protocol
frame
(header)
Fig. 5-4
Telegram structure for cyclic data transfer
Net data structure
according to PPOs
Telegram structure
for cyclic
data transfer
5 Communications via PROFIBUS DP
08.99
08.01
