Instruction Manual

276 Language Reference • Reference

Publication 1398-PM601A-EN-P — October 2000

WORDS

Variable, Volatile, User Variable

Purpose Load a user-defined variable with a value from another variable, a result of a math

expression, a constant, a timer, or an analog input.

Syntax Vn = value

variable = Vn

n The number of the variable: n = 1, 2, 3, ..., 64.

value Value can be a constant, a global variable Gn, a volatile variable

Vn, or a system variable.

variable The variable may be a nonvolatile variable Gn, a volatile vari-

able Vn, or a system variable.

Remarks G and V variables are stored internally as 4 bytes for the mantissa (the part before the

decimal point), 2 bytes for a numerator (the top part of a fraction), and 2 bytes for a

denominator (the bottom part of a fraction). The range of numbers that can be repre-

sented in 4 bytes is ±2,147,483,648. The range of numbers that can be represented in 2

bytes is ±32,767. Therefore, the range of numbers that can be contained in a G or V

variable and any intermediate value is:

The changes made to Vn remain in effect as long as power is maintained. On power-up

Vn is set to zero. If a value needs to be maintained during a power failure use a Gn

user variable. Changes made to Vn by one program will be seen by other programs.

TIP: Variables can be assigned names using the ASSIGN command and then refer-

enced by those names to make the program easier to read.