Profichip VPC3+S - PROFIBUS DP-V2

7 PROFIBUS DP Extensions
64
Revision 1.04
VPC3+S User Manual
Copyright © profichip GmbH, 2012
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.
Dout Din DXBout
DP-Slave (Subscriber)
Data Exchange with
DP-Master (Class 1)
filtered
Broadcast (Input) Data
from Publisher
Dout Din
DP-Slave (Publisher)
Data Exchange with
DP-Master (Class 1)
Dout Din
DP-Master (Class1)
Link
Response (DA=127)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
SDR
must be set to 'T
ID1
= 37 t
bit
+ 2 T
SET
+ T
QUI
'.
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.