For easy integration of this driver into the application it is handy to use: Preconfigurations in group "OPC"
|Network address||OPC-UA server IP address.|
|TCP/UDP port number||OPC-UA server port (usually 4840).|
|Ethernet transfer type||TCP|
|Not connect until first transfer||NOT checked (mandatory)|
|Close connection after every transfer||NOT checked (mandatory). After each connection, it is necessary to transfer several initialization messages and if the connection is closed repeatedly, the communication speed would be decreased significantly.|
|Server Endpoint URL||OPC-UA server endpoint URL is enetered here. |
This is used if the server allows redirecting to other servers, otherwise just enter an empty string.
The variables in the PmaCommGroup object (or even better the variables in the PmaData object with ExtComm data extension) can be of arbitrary number, type and order. The driver uses optimalised internal communication messages for reading the data from the device.
All variables are read (if the "Data refresh enabled" configurator is checked). When writing to the variable, only the single value is sent (if the "Auto send when writing to item" configurator is checked).
While being initialized, the driver registers all its variables to the OPC server (OPC system message CreateMonitoredItems) and informs the server about the requested update rate based on the settings of the "Communication refresh rate [ms]" configurator.
The the driver sends request to be updated when the values of these variables change (OPC system message PublishRequest). The OPC server than, on change of the variable, (or if there is no change, the rate defined in the "Communication refresh rate [ms]" configurator is used) sends a message containing information regarding all changed variables (OPC system message PublishResponse).
After receipt of this message, the driver immediately sends the PublishRequest message again. This way the values of the variables of the PmaCommGroup object are being updated with defined period Communication refresh rate [ms].
ItemId is the text identifier of the item that is used for addressing the value in the device. The ItemID configurator tells the driver how to receive or send the item value.
The text can be written manually, or it can be assembled in the window opened by the button to the right of the configurator.
Macro expression can be used for input (it is evaluated after starting the application).
The ItemId identifier may look like for example "ns2,str,xxxx", where:
|Time reading type||Defines whether the value time is also read along with the variable value from the OPC-UA server. |
If the time is read then this time is saved into the PmVar.TimeSource property.
No - The time value will not be read.
Source - The source time will be read, i.e. the time that the OPC-UA server read from the connected device (if the server is able to read such time).
Server - The time of the value reading by the OPC-UA server will be read.