Addtarget – Echelon OpenLNS User Manual

Page 612

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OpenLNS Programmer's Reference

575

Disconnect

DsRestoreOptions

DsSaveOption

GetDataPoint

MoveToInterface

ToString

AddTarget

Summary

Adds a single

NetworkVariable

to a hub's pending target list.

This method defines a hub network variable's pending target

list. This list is used when the Connect or Disconnect method

is invoked to create or remove a network variable connection.

Connections, as defined within OpenLNS, always consist of a

single hub and one or more complementary targets.
To create a network variable connection, follow these steps:
1. Select a single hub object and a set of one or more target

objects to connect to the hub.

2. Add the targets to the pending target list by invoking the

hub's AddTarget method for each target object (up to a

maximum of 25, see below).

3. When the list is complete, invoke the hub's Connect

method.

To remove a connection, invoke the Disconnect method,

instead.
The pending target list will only hold 25 targets at a time,

but it is cleared upon completion of the Connect or Disconnect

method. You can therefore create larger connections by

iterating through the process outlined above.
For example, upon completion of the Connect method, you

can add additional targets by invoking the AddTarget

method on the original hub object. You can then invoke the

Connect method to append the new targets to the previously

defined connection.
For network variable connections, the hub and target

variables must be complementary. A complementary

network variable is one that has a matching type/length but

the opposite direction. For example, if the hub is an output

network variable, all the targets must be input network

variables. The type or length restriction is applied depending

on the category of network variable used. When connecting

standard network variable types (SNVTs), all members of

must be the same type. When connecting user-defined

network variable types (UNVTs), all members must be the

same length.
While its basic connection model is fairly simple, LNS allows

network variables to participate in multiple connections. As

a result, it is possible to create arbitrarily complex network

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