Memory Map; Octal Numbering System; Discrete And Word Locations; Memory Locations For Discrete Memory Areas - Automationdirect.com DL05 User Manual

4–22
CPU Specifications and Operation

Memory Map

Octal Numbering
System
Discrete and Word
Locations
V Memory
Locations for
Discrete Memory
Areas
With any PLC system, you generally have many different types of information to
process. This includes input device status, output device status, various timing
elements, parts counts, etc. It is important to understand how the system represents
and stores the various types of data. For example, you need to know how the system
identifies input points, output points, data words, etc. The following paragraphs
discuss the various memory types used in DL05 Micro PLCs. A memory map
overview for the CPU follows the memory descriptions.
All memory locations and resources are
numbered in Octal (base 8). For example,
the diagram shows how the octal
numbering system works for the discrete
input points. Notice the octal system does
not contain any numbers with the digits 8
or 9.
As you examine the different memory
types, you'll notice two types of memory
in the DL05, discrete and word memory.
Discrete memory is one bit that can be
either a 1 or a 0. Word memory is referred
to as V memory (variable) and is a 16-bit
location normally used to manipulate
data/numbers, store data/numbers, etc.
Some information is automatically stored
in V memory. For example, the timer
current values are stored in V memory.
The discrete memory area is for inputs, outputs, control relays, special relays,
stages, timer status bits and counter status bits. However, you can also access the
bit data types as a V-memory word. Each V-memory location contains 16
consecutive discrete locations. For example, the following diagram shows how the X
input points are mapped into V-memory locations.
Bit #
15 14 13 12 11
These discrete memory areas and their corresponding V memory ranges are listed
in the memory area table for DL05 Micro PLCs on the following pages.
X0 X1
X10 X11
Discrete – On or Off, 1 bit
Word Locations – 16 bits
0 1 0 1 0 0 0 0 0 0 1 0 0 1 0
8 Discrete (X) Input Points
X7 X6 X5
10 9 8 7 6 5
X2 X3 X4 X5 X6 X7
X0
X4 X3 X2 X1 X0
V40400
4 3 2 1 0
1