RAM Memory Organization

Introduction

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

The RAM size is 256 Mbytes.

The RAM is composed of two areas:

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

To display the memory mapping in EcoStruxure Machine Expert, right-click on your controller in the Devices tree window and select Device Memory Info.

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 bus read-write system variables.
TMS_BUS_DIAG_R	Structure of TMS bus read-only system variables (diagnostic).
TMS_MODULE_DIAG_R	Structure of TMS modules read-only system variables (diagnostic).