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MELSEC-Q
2 THE BASICS OF AD51H-BASIC
2.6 What are Instructions and Functions?
Only instructions or functions that follow the BASIC syntax can be written in BASIC
statements. The section describes what instructions and functions are.
• Instructions
Each BASIC instruction instructs a certain processing to take place. For example,
when the PRINT instruction is used, characters will be displayed on the screen.
• Functions
Functions in BASIC return a single value in response to 1 or multiple arbitrary input
values.
Functions can only return values. Therefore, in order to use the results, they are
used in conjunction with instructions.
X
Function
A
Y
Function
A
X
Z
Instruction
Processing
There are the following types of functions.
Function
Built-in
functions
Numerical functions
Character functions
Character functions
for input/output
Special functions
User-defined functions
Built-in functions are functions already provided with BASIC. User-defined functions
are functions defined by the user using the DEFFN instruction.
