1-6
Section 1 Specifications
1-3-2 Input/output memory area
The input/output memory area is a window through which data are exchanged between the main unit (user application) and
external devices. This area is used by input devices such as pushbuttons, switches, and sensors which send data to the main
unit and by output devices such as relays, solenoids, and indicators which show the results of program executions.
G
Key points:
1) Input is represented by %I (prefix), and output by %Q (prefix). When actually assigning an I/O address, these prefixes
are followed by a size and address in the variable declaration. For details, see “1-4 I/O Address Assignment.”
2) Both input and output cannot exist in the same word.
%I %Q
IEC representation
Input/output memory
512 words
15……………………………0
………………………………………
