Rockwell-automation 2708-NBD VBASIC Language Development Kit User Manual download pdf (Page 22)

A–B

Chapter

4–1

Special Devices in A-B VBASIC

Most I/O in A-B VBASIC is performed by accessing special device names

which are unique to the workstation. In A-B VBASIC, as in Visual BASIC,

devices are accessed with the same statements as files. For example, access

to the workstation’s barcode reader is obtained by an OPEN of the device

named “BAR”, followed by GETs or LINE INPUTs.

We highly recommend use of the VBASIC Language Development Kit

(Catalog No. 2708-NBD) of subroutines for faster, easier development of

larger programs. Subroutines in that library automatically open the required

devices and perform the appropriate timeouts and formatting operations. In

addition, debugging can be done on the PC without the need for downloading

each time a program change is made. Refer to Appendix C.

Most of the following information assumes that you are not using the BASIC

Language Development Kit, but are writing a program which directly

addresses I/O devices.

Here is a list of all reserved filenames which address the special devices.

Note that they are different from DOS device names, and that they do not

contain colons:

Real Devices

Name

Front panel LCD LCD. . . . . . . . . . . . . . . . . .

Keypad KEYS. . . . . . . . . . . . . . . . . . . . . . . . .

Comm line - primary COM. . . . . . . . . . . . . .

Comm line - auxiliary AUX. . . . . . . . . . . . .

Barcode BAR. . . . . . . . . . . . . . . . . . . . . . . . .

Lights on keypad LITE. . . . . . . . . . . . . . . . .

Timer EGG. . . . . . . . . . . . . . . . . . . . . . . . . .

Host computer HOST and NET. . . . . . . . . . . . . . . . . . .

Pseudo Devices

Name

Queue to host computer QUE. . . . . . . . . . . .

User status display STAT. . . . . . . . . . . . . . . .

RAM files (any non-reserved name, 12 characters per file name max.)

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Rockwell-automation 2708-NBD VBASIC Language Development Kit User Manual Page 22