Tab: Registered Areas

The tab of the Redundancy Configuration configures the data and address ranges which are synchronized in the redundant system.

Important

On a redundant system, be careful when using file handles and operating system handles, as they can lead to different data on each of the PLCs.

Important

The method of mapping a device input to an existing project variable is not recommended. If you still do use this, then keep in mind that variables mapped in this way are not stored in the input or output data areas. This means that they are not included in the synchronization of the PLCs.

For more information, see: Synchronizing Redundant Data

Tab: Variables

Variables of POUs of type PROGRAM or of type Global Variable List can be retained redundantly in the system. You can select the POUs here.

Object

List of all objects of type PROGRAM or of type Global Variable List of the application

standard icon : The object will be synchronized.

This first means that the variables of the object have gotten the redundancy area type AREA_INPUT and are registered. At runtime, these variables are retained redundantly in the system and synchronized.

Note

When the Redundancy Configuration object exists below the application, the redundancy area type AREA_INPUT is assigned to variables by default in the declaration. This also happens if you add the object to the application later. As a result, all variables of any kind are registered by default. You can see this because these objects are selected here.

When the PLCs are started, the system is synchronized for the first time: When the second PLC starts, the redundancy data is copied from the first, active PLC to the standby PLC.

: The object will not be synchronized.

This first means that the variables of the POU have gotten the redundancy area type AREA_NONE. This means that these variables are not synchronized when the second PLC is started.

Tip

Select this option for data which have a private or local reference. For example, for diagnostic data of the fieldbus, for file handles, or for operating system handles which are valid only on the local PC.

Select All / Clear All

standard icon : Selects all objects

: Clears all objects

Note

The previous selection is overridden.

Addresses

Addresses tab: Here you can specify an area of direct addresses that should be controlled by CODESYS Redundancy. The Add button opens a dialog for defining the start and size of a Register address range. With the Edit and Delete buttons, you can change or remove existing entries.

Start

Start address of the memory area

Example: %MD48

Size

Example: 256

Add

Opens the Register address range dialog

Here you can specify a memory area.

Edit

Opens the Register address range dialog for the selected address range to be edited

Delete

Deletes the selected address range