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7 PROFIBUS DP Extensions
7.3
PROFIBUS DP-V2
7.3.1
DXB (Data eXchange Broadcast)
The DXB mechanism enables a fast slave-to-slave communication. A DP-
Slave that holds input data significant for other DP-Slaves, works as a
Publisher. The Publisher can handle a special kind of Data_Exchange
request from the DP-Master and sends its answer as a broadcast telegram.
Other DP-Slaves which are parameterized as Subscribers can monitor this
telegram. A link is opened to the Publisher if the address of the Publisher is
registered in the linktable of the Subscriber. If the link has been established
correctly, the Subscriber can receive the input data from the Publisher.
Request (FC=7)
Figure 7-7 : Overview DXB
The VPC3+S can handle a maximum of 29 links simultaneously.
Publisher
A Publisher is activated with 'Publisher_Enable = 1' in DPV1_Status_1. The
time minT
All Data_Exchange telegrams containing the function code 7 (Send and
Request Data Multicast) are responded with destination address 127. If
Publisher mode is not enabled, these requests are ignored.
64
DP-Master (Class1)
Dout
Din
Response (DA=127)
Data Exchange with
DP-Master (Class 1)
Dout
Din
DP-Slave (Publisher)
must be set to 'T
SDR
ID1
Revision 1.04
Data Exchange with
DP-Master (Class 1)
Dout
Din
DP-Slave (Subscriber)
Link
= 37 t
+ 2 T
+ T
bit
SET
QUI
VPC3+S User Manual
Copyright © profichip GmbH, 2012
filtered
Broadcast (Input) Data
from Publisher
DXBout
'.
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