Rockwell-automation 2708-NBD VBASIC Language Development Kit Manual de usuario descargar pdf (Pagina 23)

Chapter 4

Special Devices in A-B VBASIC

4–2

Some statements and intrinsic functions implicitly refer to a specific device.

These are:

Front panel LCD CLS, CSRLIN, LOCATE, POS, PRINT and WRITE. . . . .

(without file numbers)

Keypad INKEY$, INPUT$ (without filenumber),. . . . . . . . . . . .

LINE INPUT (without filenumber)

Beeper BEEP, SOUND. . . . . . . . . . . . .

Timer DATE$, SLEEP, TIME$, TIMER. . . . . . . . . . . . .

Files KILL. . . . . . . . . . . . . .

Reserved device name: LCD

These statements always access the LCD display:

PRINT and PRINT USING (without a file number)

WRITE (without a file number)

CLS

CSRLIN

LOCATE

POS

Prompts for LINE INPUT (without a file number)

As an alternative, OPEN “LCD” may be used to associate the device with a

file number and PRINT # or WRITE # used.

Note: Once OPENed, the “LCD” file CANNOT be closed.

At program start, the LCD displays the words “BASIC START”. The cursor

is at the home position and is on. The LCD is set to clear when the program’s

first character is output to it. Thus, the programmer can act as if the LCD

were actually already blank.

PRINTs to the LCD, ending without a comma or semicolon (, or ;) leave the

cursor at the start of the next line. Thus, the next PRINT causes that line to

be cleared before data is written.

PRINT statements terminated by a comma or semicolon leave the cursor

where it was at statement’s end, as shown in the following example.

Introduction (cont’d)

Device: LCD Display

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Rockwell-automation 2708-NBD VBASIC Language Development Kit Manual de usuario Pagina 23