Lenze PLC Designer PLC Designer (R3-1) - Manual (Page 118)

L-force | PLC Designer
Concepts and Base Components
116 DMS 4.1 EN 03/2011 TD29
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Broadcast addresses
There are two types of broadcast - global and local ones. A global broadcast is sent to
all nodes within a control network. The empty node address (length 0) is reserved for
this purpose.
Local broadcasts are sent to all devices of a network segment. For this purpose, all bits
of the network address are set to 1. This is possible both in relative and in absolute
addresses.
A block driver must be able to handle both broadcast addresses, i.e. empty network
addresses and network addresses with all bits set to 1 must be interpreted and sent as
broadcast.
3.11.5 Data Server
A Data Server can be added to an application in order to get access to remote data
sources. "Remote data sources" in this context means that variables (data items),
which are defined and used in other devices, can be used also in the current
application.
In contrast to the data exchange via Network Variables (fix variables lists in sender and
receiver devices, transmission via broadcasting to all network participants which own
the respective variables list) the Data Server establishes defined point-to-point
connections between the source(s) and the local application. The data items to be
exchanged are defined and it depends on their access flags, whether they get updated
in the data source resp. in the current application each time when their value changes
each on the other "side".
Using a data server is the faster alternative to providing access to data via a symbol
configuration. Unfortunately data handled via e.g. an OPC-Server cannot yet be
accessed via a data server. In this case implementing a symbol configuration is still the
modus operandi.