Rockwell Automation 2708-NBD VBASIC Language Development Kit - Manual (Page 60)

A-B VBASIC and Visual BASIC
Appendix B
Differences Between
B–12
OPEN “COM” FOR INPUT AS #1 ‘Must be a normal terminal.
DO
DO WHILE LOC(1) = 0: LOOP ‘Wait for any data in the buffer
R$ = INPUT$(1, #1)
Rx$ = Rx$ + R$
i = INSTR(Rx$, CHR$(13))
‘Look for a carriage return.
IF i > 0 THEN
Datain$ = LEFT$(Rx$, i – 1) ‘Read in data
CLS
PRINT Datain$;
‘Display it
Rx$ = “”: R$ = “” ‘Clear the temporary buffer
END IF
LOOP
LOCATE[row][,[column][,[cursor]]]
Moves the cursor to the specified position. The start and stop arguments do
not apply to A-B VBASIC.
LOCATE 2, 1 ‘Position cursor on line 2
PRINT “Hello world”; ‘Use of semicolon prevent scrolling
LOCATE 1, 1, 0 ‘Position cursor on line 1
PRINT “Goodbye world”;
LOF(filenumber)
Returns the length of the named file in bytes. The REMARKS paragraph in
the VBDOS manual applies only to some A-B VBASIC devices. See the
chapter on Special Devices for details about specific devices.
OPEN “POWER” FOR INPUT AS #1
IF LOF(1) > 0 THEN
‘If file contains data,
Powerfail = TRUE then there must have been a power failure
ENDIF
LTRIM$(stringexpression)
Returns a copy of a string with the leading spaces removed.
A = 100
A$ = LTRIM$(STR$(A)) ‘Removes leading space in front of 100.
MID$(stringexpression, start[, length])
Returns a substring of a string. See VBDOS manual for detailed
information. See also MID$ statement, (replaces a portion of a string
variable with another string.)
A$ = “Now is the time for...”
B$ = MID$(A$, 8, 3) ‘B$ now equals “the”.
MKD$, MKI$, MKL$, MKS$
(MKD$ is no longer supported) Converts numeric values to string values.
See VBDOS manual for detailed information.