Owner's Manual (Complete)

Chapter 10—Programs and the Visual Programmer
24 The Home Control Assistant
Trigger Evaluation
There are a few important additional points to consider when using Weather triggers, Flag triggers,
and Expression triggers.
The properties of the trigger define when the program starts. For example, the trigger "When the
outside temperature is over 80" starts the program when the weather provider tells HCA that the
outside temperature has risen to 80. But when does the program start again? The temperature may
stay above 80 for several hours. Does the program start each time a weather observation is made?
No. The program only starts the first time the temperature is reported over 80. The temperature
must drop back below 80 and then rise above 80 before the program starts again.
Think of the trigger being in two possible states:
Ready to trigger and triggered. If the
temperature is under 80, then the trigger is
ready. Once it goes over 80 the program starts because
the trigger has
triggered. It can't trigger again until it first goes back to the Ready state.
This is the same logic used by the Flag triggers and expression trigger. The expression must
evaluate to NO to be
ready, then evaluate to YES to trigger and then back to NO to become Ready
again.
The last important point is that HCA evaluates expression and weather triggers about every 60
seconds. This means that the expression trigger is only looked at once a minute. If the condition
the expression is based upon changes more rapidly than once a minute, HCA may miss some of
those changes.
Setting properties for program elements
Now that you know how programs start and how to draw them using the program canvas, let’s look
at the elements of those programs, and see what they can do. You control what an element does by
setting its properties, using the properties dialog box specific to that element.
Hint: Most programs will not use all the different types of elements that HCA provides. The
sample file provided when you installed HCA contains several simple and several complex
programs. A good way to learn about the Visual Programmer is to take a look at what these
programs do.
web tip: Refer to the technical notes section on the web site for more information on the MyHome
sample file and its programs.
There are two ways that you can open the properties dialog box for an element. The first way is
automatic: as you add an element to the program canvas, its dialog box opens so that you can set
the properties for the element.
The second way is to use the right mouse button:
 Click an element and choose Properties from the popup menu or double click on the element.
The dialog box for the element opens so that you can enter or change its properties.
Elements
This section lists the various elements used in programs and provides details about how you can set
and use their properties. The properties dialog boxes for the elements are very similar and very
easy to use. They have different components, many of which will be familiar to you.
Note all elements are fully explained here. Some are very specific to some automation hardware.
These are fully explained in the appendix for the hardware they apply to.