Dynapro Technologies Dynapro ET TCS, Руководство разработчика приложений

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The Read Screen Existence command provides a way for the host to determine if a particular
screen exists. The command inquires about the existence of one screen at a time. The Displayed
Screen always exists; any other screen exists only if it was stored in nonvolatile screen memory
before power-up or if the host created it since power-up by referring to it in one of the following
commands:
•
Initialize Screen Command
•
Select Screen Command
•
Copy Screen Command
An example use of the Read Screen Existence command is in an installation where the host
communicates with a set of TCSs each of which has a different collection of screens. The host
can send a Read Screen Existence command to determine which screens a particular TCS
contains.
This command can also be used to determine if a screen still exists if power was lost just as the
host was manipulating the screen. After power is restored, the host can send a Read Screen
Existence command to determine whether the screen still exists.
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None. (This is a remote command only.)
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<ESC>[>12;<Pscr>n
<Pscr> is a numeric parameter from 0 through 256 that specifies the number of the screen
whose existence is to be reported. Displayed Screen is 0, stored screen is non-zero.
If <Pscr> is omitted or 0, the existence of the Displayed Screen is reported (it always
exists).
The TCS responds:
<ESC>[>12;0n
if the screen does not exist
<ESC>[>12;1n
if the screen exists
NOTE
The report may differ from the above format if the Reporting Format command has been issued. Refer to
the Reporting Format command description in Chapter 4 for details.