
Overview of PROFIBUS DP
DP Base Programming Interface for CP 5613/CP 5614
C79000-G8976-C108-01
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2.6 Modes of the DP Master
Overview
During communication with the DP slaves, the DP master can adopt the following
four modes:
x OFFLINE
x STOP
x CLEAR (or AUTOCLEAR)
x OPERATE
Modes
Each of these modes is characterized by defined actions between the DP master
and the DP slaves.
Master
Mode
Meaning
OFFLINE No communication between the DP master and DP slaves.
This is the startup mode of the DP master.
STOP In this mode, there is also no communication between the DP
master and the DP slaves. In contrast to the OFFLINE mode, a
DP diagnostic station (DP master class 2) can read out
diagnostic information from the DP master.
CLEAR
(or
AUTOCLEAR)
All the DP slaves entered and activated in the database are
assigned parameters and configured in this mode. This is
followed by the cyclic data exchange between the DP master
and DP slaves. In this CLEAR mode, the value 0 or empty
frames are sent to all slaves with a process output; in other
words, process output is deactivated. The input data of the
slaves are known and can be read out.
OPERATE
The cyclic, productive data transfer to the DP slaves takes
place in the OPERATE mode. This is the productive phase. In
this mode, the DP slaves are addressed one after the other by
the DP master. The call frame transfers the actual output data
and the corresponding response frame transfers the actual
input data.
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