Direct Data Exchange - Siemens SIMATIC S7-300 Hardware And Installation Manual

Commissioning

9.7.3 Direct data exchange

Requirement
In 7 STEP 7 V 5.x or later, you can configure "Direct data exchange" for
PROFIBUS nodes. CPUs 31x-2 DP/31xC-2 DP can participate in direct data
exchange both as sending or receiving station.
Definition
"Direct data exchange" is a special communication relationship between
PROFIBUS-DP nodes.
Characteristic of direct data exchange is that PROFIBUS DP nodes "listen" on the
bus for data a DP slave returns to its DP master. This mechanism allows "Listening
stations" (receivers) direct access to modified input data of remote DP slaves.
Address Areas
In your STEP 7 configuration of the relevant peripheral input addresses, specify
which address area of the receiving station is to receive data requested from the
sending station.
A CPU 31x-2 DP/31xC-2 DP can operate as:
• DP slave sending station
• receiving station, as DP slave or DP master, or as CPU not integrated in a
master system.
9-36
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02