Communication protocol 137
Parameter handling in cyclic communication (DP)
In cyclic PROFIBUS DP communication, parameter data is
transferred in PPO message types 1, 2 and 5, as shown in section
PPO types on page 135. The parameter identification part consists
of eight bytes, as shown below.
The Request label is used by the master when transmitting data to
the slave, while the Response label is used by the slave as a
positive or negative acknowledgement. The tables below show the
Request/Response functions.
Request labels (from master to slave)
Request Function Response labels
Ackn. (+) Ackn. (-)
0No task 0 –
1 Request parameter value 1, 2 7
2 Change parameter value (word) 1 7, 8
3 Change parameter value (double
word)
27, 8
4 Request description element 3 7
5 Change description element 3 7, 8
6 Request parameter value (array) 4, 5 7, 8
ID IND VALUE
15 14131211109876543210
Request label
Response label
Request signal
Parameter number (PNU)
Process data
Parameter
identification
Not used (=0)
CW REF
(PD1, PD2...)
SW ACT
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