Installation guide
There are a few situations, however, in which your choices for Link Master are limited or are made
for you:
l
If one of the participants is a read-only control, the read-only control is always the Link
Master because its value cannot be changed by software. In this situation, the ability to
change the Link Master is disabled.
l
Dynamic selectors (such as the Selector on DR2s and DR3s) cannot be Link Master because
they have no value when they are not active in a control link. The ability to configure
dynamic selectors as the Link Master is disabled.
In summary, there are three ways in which a control link's Link Master designation is created:
1. You create the control link.
2. You manually change the Link Master designation for the control link.
3. You add a read-only control to the control link.
NOTE: Because Command control links do not maintain a state or hold a value, these control links do
not need a Link Master.
Best Practices
What are some best practices to follow when creating and working with HALîSystem con-
trol links?
BEST PRACTICE: Always drop any new control link participant onto a control already participating in
the link. In other words, the control link target
1
should always be an existing participant. Think in
terms of what it is that you want to control.
BEST PRACTICE: Name your links as you create them to help with identification later. For example, if
you want to see the links in which a control is participating, the list of links will only make sense if
each one is aptly named.
1
The control onto which you will drop one or more other controls to create a control link. Think of the control
link target as a bucket into which you place all the other controls participating in the link.
HAL SYSTEM DESIGN GUIDE
119