dl-breadcrumbs__homedl-breadcrumb-item__separatorConfiguration and programmingdl-breadcrumb-item__separatorProgramming with CODESYSdl-breadcrumb-item__separator...dl-breadcrumb-item__separatorCODESYS Development Systemdl-breadcrumb-item__separatorWorking with Controller Networksdl-breadcrumb-item__separatorData Link with Data Sourcesdl-breadcrumb-item__separatorUpdating data interfaces
dl-pagination__prev-inactivedl-pagination__prev-activedl-pagination__next-inactivedl-pagination__next-active
Updating data interfacesdl-permalink__symbolPermalink

The data source variables are updated cyclically in runtime mode. Only the data is updated that either is used in the current visualization or has the property “Update always”.

You can define the time interval. Moreover, you can define variables whose data is transferred in each update interval, and therefore they are always update. To update variables that are not used in the application code, you can implement an update programmatically with the help of interface functions from the data source manager.

NOTICE

NOTICE
NOTICE
NOTICE

NOTICE

NOTICE

If data traffic between the remote and local device is too high, then the update rate is reduced automatically. This can lead to an incomplete transfer.

Setting the update rate

  1. Open the editor of the data source.

  2. Click the “General and Diagnosis” tab.

  3. Specify a value in the “Update rate” field.

    Example: ‎100‎

    The data from the remote device to the local device is transferred every 100 ms.

Selecting the variable for 'Update always'

NOTICE

NOTICE
NOTICE
NOTICE

NOTICE

NOTICE

Avoid updating too many variables always. Each update produces additional data traffic at the connection between the remote and local devices. When data traffic is too high, the update rate is reduced automatically. This can lead to an incomplete transfer.

  1. Open the editor of the data source.

  2. Activate the option “Update always” for a variable.

    The data of the variables is transferred at each update cycle, even when the data has not changed.

Updating data programmatically

The data source manager provides interface functions in the ‎Datasources‎ library. If a data source manager is integrated in the application code, then the global variable ‎g_Datasources‎ is instantiated automatically. This provides access to the interface functions.

Then you can update individual variables that are not called in the active visualization.

Example

The variable ‎ivar‎ is activated and deactivated by means of methods from the ‎Datasources‎ library so that its value is transferred. Furthermore, you can configure that the variable is updated only over a defined duration in order to save transfer capacity.

//Synchronize with DatasourcesTask and block until access is possible 
//Regard the feedback in ERR_OK or in ERR_DE_MULTITASKING_LOCKED
g_Datasources.BeginDataConfiguration(TRUE);  
// Activate variable
g_DataServer.UseData(ADR('RemoteDevice.Application.PLC_PRG.iVar'));
// Deactivate variable
//g_DataServer.ReleaseData(ADR('RemoteDevice.Application.PLC_PRG.iVar')); 
g_DataServer.EndDataConfiguration();

The data configuration is started with ‎BeginDataConfiguration(TRUE)‎, thus initializing the synchronization of the task ‎DatasourceTask‎ with the application task. The value ‎TRUE‎ blocks the processing until the access to the variable is possible; ‎FALSE‎ repeats access attempts without blocking. The return values ‎ERR_OK‎ and ‎ERR_DS_MULTITASKING_LOCKED‎ provide feedback about the access attempts.

When synchronization is successful, the variable is activated by means of the ‎UseData‎ method. Then the data configuration is completed with the ‎EndDataConfiguration‎ method and the synchronization triggered again with the task ‎DatasourceTask‎.

The ‎ReleaseData‎ method is used in the same way for deactivating the variable again at the desired processing time.