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LNS Programmer's Guide

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Use permanent monitor sets when you need to create monitor points that will be used

often, or in multiple client sessions. If you need monitor points that will only be used

once, or in a single client session, you should use temporary monitor sets.

Temporary Monitor Sets

Temporary monitor sets are opened automatically by LNS as they are created, and can

only be accessed from the client that created them. They cannot be accessed from the

permanent MonitorSets collections described in the previous section. When a client

releases a temporary monitor set, or when the client session in which a temporary

monitor set was created ends, the temporary monitor set and all the monitor points it

contains are deleted automatically.

If you need to create a group of monitor points that you can use in multiple client

sessions or that you intend to use multiple times, you should use the permanent monitor

sets described earlier in this chapter. However, temporary monitor sets take less time

and network resources to create. This may be useful if you only need to monitor a device

while you are installing it on a network, or if your application will not need to monitor

the device on a regular basis.

The properties and methods that can be used on temporary monitor sets and temporary

monitor points are generally the same as those that can be used on permanent monitor

sets and permanent monitor points. However, there are a few exceptions to this rule.

Temporary MonitorSet objects cannot be created or used by Independent client

applications. The Open() and Close() methods have no effect on temporary

MonitorSet objects, because temporary MonitorSet objects are opened as soon as they

are created, and closed as soon as the client application releases them, or the session in

which they were created ends. For more information on creating monitor sets, see the

Creating Monitor Sets section later in this chapter.

You should also note that temporary monitor sets are not enabled as they are opened.

You must explicitly enable temporary monitor sets and temporary monitor points with

your application using the applicable Enable() method. For this purpose, the

MsgMonitorPoint object now includes an Enable() method. For more information on

enabling monitor sets and monitor points, see Opening and Enabling Monitor Sets on

page 213.

The DefaultOptions properties of MsgMonitorPoint and NvMonitorPoint objects in

temporary monitor sets are not accessible. The values applied to these properties are

taken from the temporary monitor set’s MsgOptions or NvOptions properties. For more

information on monitor and control options, see the Managing Monitor Sets section later

in this chapter.

Monitor points in temporary monitor sets do not support the use of connection

description templates to define certain monitoring options, as monitor points in

permanent monitor sets do. As a result, you must set the connDesc element to NULL

when you use the Add() method to add a message monitor point or network variable

monitor point to a temporary monitor set.

There is one other variance you should note when using temporary MonitorSet objects.

Network variable monitor points in temporary monitor sets cannot be automatically

bound to the monitoring node. This means that the UseBoundUpdates property of all

temporary monitor sets and monitor points must be set to False. For more information

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