Galil Motion Control note 3311a Page 1

**DMC-1000**

**DMC-1500**

**DMC-1300**

**Application Note 3311a: Representation of Numbers**

**Specifying Numbers:**

Numbers are stored as 6 bytes of information. The six bytes are represented as 4 bytes of

integer and 2 bytes of fraction. Thus, the integral part of the number can have values

between +/- (2

31

-1) **or +/- **2147483647.

**Avoid Calculation Errors:**

The fractional part of the number is represented with a resolution of 2 bytes **or** 1 part in

2

16

**or** 1 part in 65536. The fractional resolution can cause unexpected calculation

errors if this is not well understood.

**Example #1:**

let X = .001

let Y = 819200

The Galil goes through the following calculations:

X = 66/65536

Y = 819200

X*Y

=

54067200/65536

=

825

The actual value of the product of X and Y is 819.2

**Example #2:**

let X = (286*.001*6350)-25250

The true value of X is -23433.9

The Galil calculates the value of X as -23421.0419

A more accurate calculation will occur if the calculation is re-arranged in the following

manner:

X = ((286*635)-2525000)/100

The Galil calculates the value of X as -23433.9