Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 167)

Chapter
Statements 11
11 -15
Use the IF-THEN-ELSE statement to set up a conditional test.
If you want to transfer control to different line numbers using the IF
statement, you may omit the GOTO statement. These examples give the
same results:
>20 IF INT(A)<10 THEN GOTO 100 ELSE GOTO 200
or
>20 IF INT(A)<10 THEN 100 ELSE 200
You can replace the THEN statement with any valid BASIC module
statement:
>30 IF A<>10 THEN PRINT A ELSE 10
>30 IF A<>10 PRINT A ELSE 10
You may execute multiple statements following the THEN or ELSE if you
use a colon to separate them:
>30 IF A<>10 THEN PRINT A : GOTO 150 ELSE 10
You may omit the ELSE statement. If you omit the ELSE statement
control passes to the next statement.
>1 REM EXAMPLE PROGRAM
>20 IF A=10 THEN 40
>30 PRINT A
Syntax
IF rel expr THEN valid statement ELSE valid statement
Example
>1 REM EXAMPLE PROGRAM
>10 IF A =100 THEN A=0 ELSE A=A+1
Upon execution of line 10 IF A is equal to 100, THEN A is assigned a
value of 0. IF A does not equal 100, A is assigned a value of A+1.
IF-THEN-ELSE