Rockwell-automation 2708-NBD VBASIC Language Development Kit Manual de usuario descargar pdf (Pagina 24)

Chapter 4

Special Devices in A-B VBASIC

4–3

Note: See the description of PRINT USING and WRITE for details on other

formatting options supported.

See also the READ.BAS collection of BASIC Language Development Kit

subroutines for useful LCD output subroutines, including automatic

formatting of display lines, automatic clearing of the display, and cursor

positioning.

CLS

Name$ = “Fred”

PRINT “Please Enter Now!”

PRINT “Thank You”; Name$; ‘ Keep cursor on second line.

CONST ScreenDev = 1

OPEN “LCD” FOR OUTPUT AS #ScreenDev ‘ Cannot be CLOSEd

LineWidth% = LOF (ScreenDev) \ 2 ‘ Width of display.

PRINT #ScreenDev, “Please Enter Code:”; ‘ Cursor remains on line.

LINE INPUT, Code$

Reserved device name: KEYS

These statements always access the Keypad:

INPUT$ (without a file number)

LINE INPUT (without a file number)

INKEY$

When a Keypad line is being entered with LINE INPUT, only the enter and

backspace keys perform the expected termination and correction functions.

As an alternative, INPUT$ and LINE INPUT can be used to access this

device using OPEN “KEYS”.

The BASIC Language Development Kit (Catalog No. 2708-NBD) modules

READ.BAS and MENU.BAS contain several helpful subroutines for

obtaining input through the Keypad.

CONST KeyDev = 1 ‘ Assign device a file number

OPEN “KEYS” FOR INPUT AS #KeyDev ‘ Open device.

DO WHILE a$ = ” ”: a$ = INKEY$: LOOP ‘ Wait for a key stroke.

LINE INPUT “Enter your name: ”; Name$ ‘ Must press enter.

b$ – INPUT$ (1) ‘ Another way to get a key stroke.

Device: LCD Display

(cont’d)

Device: Keypad

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Rockwell-automation 2708-NBD VBASIC Language Development Kit Manual de usuario Pagina 24