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Parameters - page of object PmaOpcClientGroup

Description:
Definition of the data group parameters of the OPC client, the data that are to be shared with the connected OPC server.
Common configurators:
Active after startIf checked, then the group becomes active immediately after starting the application.

This configurator sets the initial value of the property ActiveGroup.

Configurators for receiving the data from the OPC server:
Update from server at server changeIf checked, then automatic data refresh from the server right after starting the application is enabled (the data to be refreshed are defined on the "Data" page and the data in the PmaData object containing ExtOpcClient).

This configurator sets the initial value of the property Update.

If this configurator is not set, then the data can be received by the method Refresh or Read.

Minimum update rate [msec]Rate in milliseconds. At the automatic update the OPC server won't send data faster than it is set here.

This configurator sets the initial value of the property UpdateRate.

Deadband [%]At the automatic update the OPC server won't send data that changed less than entered here.

This configurator sets the initial value of the property Deadband.

"onDataReceive" eventThe onDataReceive event calling type. The OPC server usually sends multiple data items simultaneously and here it is defined for which received variables the event is triggered and what will be saved in the pEvent.Items parameter of this event.
A = call the event for all registered variables (in this object and also in other PmaData objects) - The event is triggered for all variables that have received values. These are:
- variables defined in this PmaOpcClientGroup object on the "Data" page.
- variables defined in the PmaData object that have ExtOpcClient data extension registered into this PmaOpcClientGroup object.

In the onDataReceive event, in the pEvent.Items parameter there will be a list of data extensions of these variables (objects of the ExtOpcClient type).

B = calling for the whole group of received variables - only for variables defined in this object (obsolete) - The event is triggered only for variables that have received values that were defined in this object on the "Data" page. The event is triggered only once for each received group of variables.

In the onDataReceive event, in the pEvent.Items parameter, there will be a list of variables (objects of the PmVar type).

C = calling for each variable separately - only for variables defined in this object (obsolete) - The event is triggered only for variables defined in this object on the "Data" page, that have received values. The event is triggered for each variable individually. For example if there is agroup of 100 variables received, then the event is triggered 100 times. That is the main reason why this approach is not recommended for large volumes of data items.

In the onDataReceive event it is possible to check the received variables from the pEvent.VarName parameter.

Configurators for sending data to the OPC server:
Auto send to server when writing to itemIf checked, then at any writing into the variable the value of this variable is immediately written to the OPC server (at writing into data defined on the "Data" page and at writing into PmaData object data containing ExtOpcClient).

If you write into more items of this object at a time, then the transfer is invoked for each item separatelly! Then it is better to disable this configurator and to send the data by the Write method.

Caution! Writing to the OPC is called only if the real write is performed (e.g. object.Item(0).Value=3) into the item - let's mark it A. But if the data binding (during the reading) to another item B (in another object) is defined in the item A and it is written into the item B, then the item A doesn't know about the change and nothing is sent to the OPC server (the item A does know about the change only when it is read by someone - data binding is then "performed").

PROMOTIC 9.0.7 SCADA system documentation - MICROSYS, spol. s r.o.

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