Overview

The Memory tab is only available for the Modicon M340 hardware platform equipped with a State RAM memory area.

It allows defining the type of memory management for the selected input / output module.

The option you select here must comply with the type of memory management you selected for the processor.

The following settings are possible:

If...

Then...

Topological memory management is configured for the processor

you can only select Topological memory management for the discrete and analog modules.

Mixed topological and State RAM memory management is configured for the processor

you can select either Topological or Mixed topological and State RAM memory management for the discrete and analog modules.

The memory management settings of the modules are compared with the memory management settings of the processor during Analyze. If any inconsistencies are detected, an appropriate message is displayed in the output window.

The type of memory management you selected for the processor will be used as default setting for the Memory Management parameter in the Memory tab.

Any application made with Control Expert is automatically configured with address configuration for topological addressing as the default setting.

NOTE:

If you want to import a legacy LL984 Compact application which uses Modbus request to communicate with an HMI, you have to use State RAM addressing to preserve the Modbus exchange between PLC and HMI.

Specific Configuration Dialogs in Case of LL984 Import

If an ST section has been created during import to emulate Compact configuration behavior, the converter creates a specific I/O module configuration with specific configuration dialogs.

The Memory Management area is grayed and the choice is fixed to Mixed topological and State RAM.

In the State RAM area Format and Coding are defined by the converter.

You can only delete these modules. Copy and paste of these modules is not possible.

Memory Management

The area Memory Management of the Memory tab provides the following options:

Option

Description

Topological

Select this option to work with pure topological addressing.

If this mode is selected, the parameters in the State RAM area of this dialog box are disabled.

Mixed topological and State RAM

Select this option to work with State RAM addressing for IO access.

Topological addressing remains possible for some IO objects (%CH, %I.ERR, ...) but it’s not possible to access IO values (%I, %Q).

With this option selected, define further State RAM options in the State RAM area of this tab for the different types of modules.

NOTE: With this type of memory management, all channels are associated with only one task (MAST or FAST).
NOTE: If you select Mixed topological and State RAM for Memory Management the following online features are disabled:

  • I/O Objects

  • Memory

  • Debug

  • Fault

State RAM Configuration for Discrete Modules

Depending on the selected module, the State RAM area of the Memory tab contains parameters for discrete input modules, discrete output modules or for discrete mixed modules. They are available if the option Mixed topological and State RAM is selected in the Memory Management area.

The figure below shows the Memory tab for a discrete mixed input / output module as an example:

The State RAM area contains the following parameters:

Parameter

Description

Format

  • Bit: Select this option for channel mapping in the discrete mode. This means that each channel is mapped to a %I (inputs) or %M (outputs).

  • Word1: Select this option for channel mapping in the word mode. This means that a group of 8 channels is mapped to a %IW (inputs) or %MW (outputs).

Coding

This parameter is only available for channel mapping in word mode, that is if the parameter Format is set to Word.

  • Binary: Select this option to use the binary integer format.

  • BCD: Select this option to use the BCD coding format.

Mapping

This parameter allows you to define the starting addresses for the inputs and outputs.

The following sizes of the memory areas are possible:

  • For inputs in Bit format: %I-1x

  • For inputs in Word format: %IW-3x

  • For outputs in Bit format: %M-0x

  • For outputs in Word format: %MW-4x

NOTE: The State RAM address starts at address 0, but the first available address for discrete and analog modules is %I1, %M1, %IW1, and %MW1.

(1) When Word is selected as the Format, the LSB of the Word is mapped to:

  • Input 0 on discrete input modules

  • Output 0 on discrete output modules

NOTE: All channels of a discrete module must be configured. It is not possible to leave a group of channels un-configured.
NOTE: You can use State RAM objects in event sections, but they are refreshed with the frequency of the task where they are declared.
NOTE: State RAM addresses are not checked during input. If any range overlapping is detected or any address exceeds the range of the State RAM, an appropriate message is displayed at the validation screen or during Analyze .

State RAM Configuration for Analog Modules

Depending on the selected module, the State RAM area of the Memory tab contains parameters for analog input modules, analog output modules or for analog mixed modules. They are available if the option Mixed topological and State RAM is selected in the Memory Management area.

The figure below shows the Memory tab for a mixed analog input / output module as an example:

The State RAM area contains the following parameters:

Parameter

Description

Mapping

This parameter allows you to define the starting addresses for the inputs and outputs.

The following sizes of the memory areas are possible:

  • For inputs in Word format: %IW-3x

  • For outputs in Word format: %MW-4x
NOTE: State RAM addresses are not checked during input. If any range overlapping is detected or any address exceeds the range of the State RAM, an appropriate message is displayed at the validation screen or during Analyze . For instance, if a located variable is created in the Data Editor, using a %MW IO map word of a configured IO base, the following build error will occur: ‘Error: Memory overlapping with protected memory address '%MWi'. Please relocate the resources in '%MWi' to avoid overlapping.’ (%MWi is the address that have to be changed in the DataEditor).