Dynapro Technologies Dynapro ET TCS, Application Developer'S Manual

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D-15
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The Select Screen Command provides a convenient way for the host to select any screen for
editing. Usually, the host selects the Displayed Screen in which case editing changes are visible
as they are made.
Sometimes the host may select a stored screen to be edited. This is a very powerful capability
since a stored screen can be edited invisibly to the user. Even though the host is editing the stored
screen, the user only sees the Displayed Screen which is not changing.
When selecting a stored screen for editing using the Select Screen Command, keep the following
points in mind:
•
While a stored screen is selected by the Select Screen Command, all screen-dependent
editing commands sent to the TCS affect only the invisible stored screen. The contents of the
Displayed Screen do not change. Therefore, it may appear that the editing commands are not
taking affect. In fact they are, but the results become visible only when the stored screen is
copied into the Displayed Screen.
•
If memory is nearly full and the host is already editing another stored screen which is too
large to be stored , then an Expansion Memory Full error occurs. Unless the host is polling
the TCS using the Request Error Status command or the Error Interrupt Mode is set, the host
will not be aware of the error. Screen-dependent editing commands which follow will not be
sent to the stored screen since the Select Screen Command did not take affect. Instead, the
editing commands affect the previous stored screen which remains selected. To select any
other screen, the stored screen which has become too large must be simplified, or another
stored screen must be deleted to make more room .
NOTE
Expansion Memory refers to the 96K of nonvolatile memory available for Screen and
Dynamic Font Storage.