Rockwell-automation 2708-NBD VBASIC Language Development Kit Instrukcja Użytkownika Pobierz pdf (Strona 56)

A-B VBASIC and Visual BASIC

Appendix B

Differences Between

B–8

may not return the same file numbers, even in identical programs. Just

because a file number is unassigned does not imply that a new file can be

created. There is a maximum number of files which can exist, open or not.

See the Limits section for specifics on A-B VBASIC file and device

limitations.

IF NumFilesOpen < 15 THEN NextFileNum = FREEFILE

FUNCTION name[(parameterlist)][STATIC]

Declares the name, the parameters, and the code that form the body of a

FUNCTION. The appearance of a FUNCTION’s name on the right side of an

= or in an argument list, is considered to be a call to that function, with or

without an “(argument list)”. Do not use FUNCTION procedures that

perform I/O in I/O statements.

CurrTime$ = GetTime$

FUNCTION GetTime$()

GetTime$ = TIME$

END FUNCTION

GET [#]filenumber[,[recordnumber][,variable]]

Reads data from a file in memory into a variable. All 3 items after GET are

required, however the record number can be consecutive commas as in, GET

#1,,V$. See the chapter on Special Devices for details about input from

specific devices. FIELD is not supported, use TYPE..END TYPE.

TYPE EmpType

Badge AS STRING * 8

Name AS STRING * 25

END TYPE

DIM SHARED Emp AS EmpType

OPEN “EMPLOYEE” FOR RANDOM AS #1 LEN = LEN(Emp)

Rec = 0

DO WHILE NOT EOF(1)

Rec = Rec + 1

GET #1, Rec, Emp

IF Emp.Badge = BadgeInput$ THEN Found = TRUE: EXIT DO

LOOP

CLOSE #1

GOSUB {linelabel | linenumber}....RETURN

Branches to and returns from a sub–routine. Linelabel on RETURNs are not

supported in A-B VBASIC. BASIC’s SUB and FUNCTION procedures

provide a more well–structured alternative to GOSUB...RETURN

subroutines.

CurrTime$ = LEFT$(GetTime$,4)

IF CurrTime$ > OldTime$ THEN

GOSUB UpdateTime

OldTime$ = CurrTime$

1 2 ... 51 52 53 54 55 56 57 58 59 60 61 ... 83 84

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