Rockwell Automation 2708-NBD VBASIC Language Development Kit - Manual (Page 14)

an A-B VBASIC Program
Chapter 2
Developing and Running
2–3
The .LXE “download” file produced the the A-B VBASIC cross-compiler
must be transmitted, through the Master Workstation, to the target
workstation. This transmission must honor whatever protocol has been
chosen for Host-Master communication in the Setup menus on the
workstation: XON/XOFF, Polled Mode, Request Response, or whatever
other method is enabled. In particular, the following will NOT WORK:
COPY PGM.LXE COM1
This WON’T WORK, since the standard DOS communication drivers do not
implement XON/XOFF.
Downloading a BASIC program in .LXE format will terminate any program
in progress at the start of the downloading process. Successful completion of
a download results in the initiation of the new program. However, a program
that is in .PGM format (described in Chapter 3) can be downloaded into
RAM without interrupting the currently running program. The .PGM format
program can later be executed by calling it with a CHAIN statement.
This section summarizes the status of the workstation when a program starts.
LCD:
The front panel display may be thought of as being blank. The first character
output will appear in the upper left corner of the display. The cursor is on.
The words “BASIC START” are placed on the display by the operating
system before the BASIC program is initiated. If this text is visible long
enough to be noticed, the probable cause is a BASIC program which has not
yet reached a PRINT statement.
Random numbers:
The random number seed is set to 1.
RAM files:
All files are closed but their contents, if any, remain unchanged.
Variables:
Are 0 or null string per Visual BASIC defaults.
Host device:
The Host device is closed and therefore any data collected by the workstation
and queued is held until an OPEN “Host” command is encountered.
Loading and Auto-Starting
an A-B VBASIC Program
Start-up Condition of
an A-B VBASIC Program