RAM Memory Organization

Introduction

This section describes the Random Access Memory (RAM) size for different areas of the Modicon M262 Logic/Motion Controller.

Memory Mapping

The RAM is composed of two areas:

oDedicated application memory

oOS memory

This table describes the dedicated application memory:

Area	Element
System area	System Area Mappable Addresses %MW0...%MW59999
	System and diagnostic variables (%MW60000...%MW60199) This memory is accessible through Modbus requests only. These must be read-only requests.
	Dynamic Memory Area: Read Relocation Table (%MW60200...%MW61999) This memory is accessible through Modbus requests only. These must be read-only requests.
	System and diagnostic variables (%MW62000...%MW62199) This memory is accessible through Modbus requests only. These can be read or write requests.
	Dynamic Memory Area: Write Relocation Table (%MW62200...%MW63999) This memory is accessible through Modbus requests only. These can be read or write requests.
User area	Symbols
	Variables
	Libraries
	Application

System and Diagnostic Variables

Variables	Description
PLC_R	Structure of controller read-only system variables.
PLC_W	Structure of controller read/write system variables.
ETH_R	Structure of Ethernet read-only system variables (Ethernet counters).
ETH_W	Structure of Ethernet read/write system variables. Allows you to reset Ethernet counters.
SERIAL_R	Structure of Serial Line read-only system variables (Serial Line counters).
SERIAL_W	Structure of Serial Line read-write system variables. Allows you to reset Serial Line counters.
TM3_MODULE_R	Structure of TM3 modules read-only system variables.
TM3_BUS_W	Structure of TM3 modules read-write system variables.
TMS_BUS_DIAG_R	Structure of TMS modules read-only system variables (diagnostic).
TMS_MODULE_DIAG_R	Structure of TMS modules read-only system variables (diagnostic).

For more information on system and diagnostic variables, refer to the M262 System Library Guide.