Specifications

A - 12 RSLinx – Training Guide
How to monitor which topic within an Alias is
currently active
The information in this technote applies to:
Product:
RSLinx
Type:
Application Note
Technote ID:
A1143
Package/Mod
ule(s):
RSLinx (All)
Modified:
03/01/99
Revision(s):
N/A
Fixed In
Revision:
N/A
Sub-
System(s):
DDE Server
Technical Note Details:
Background:
RSLinx's "Alias" topic allows users to specify alternate communications paths.
For example, a user could configure an alias called "MyAlias" consisting of many
topics. If the first topic stops communicating, the Alias can automatically switch
to the next topic as needed. This switchover is completely transparent to the
application, which only sees the alias topic.
In some applications, a user may wish to indicate which topic within the alias is
the currently active topic. This can allow an application such as RSView to
display an indicator to an operator that a problem exists. It can also allow an
application to take some sort of programmed action when a communications
failure takes place.
Solution:
RSLinx provides an indicator for each alias topic called "ActiveTopic". The
following DDE link will return the name of the active alias topic:
RSLinx!AliasTopicName|'Activetopic'