On a Geo SCADA Expert system, you configure the Geo SCADA Expert database so that entries in the database reference the devices and plant that you are trying to monitor on your system. This section summarizes the database items that you need to configure in order to read and write to data on other servers, using the OPC XML-DA protocol.
To communicate with other servers using the OPC XML-DA protocol, the OPC XML-DA Client Driver has to be installed and running on the Geo SCADA Expert servers on your system.
When you configure OPC XML-DA items in the Geo SCADA Expert database, many of the settings for those items need to correspond to the settings on the relevant OPC XML-DA servers on your system. You need to have access to, or a list of, these settings before you can configure the OPC XML-DA database items successfully.
For instance, you need to know the read mechanism that is supported by the OPC XML-DA servers on your system, and the user names and passwords that allow the required level of access to the data on those servers.
You also need to be aware of which optional features are required for each OPC XML-DA item. These features include:
- Alarm views
- Alarm redirections
- Historic data storage
- User methods.
You can also use core Geo SCADA Expert features with OPC XML-DA database items, including Lists, Actions, and Mimics. See the core documentation for details.
For each OPC XML-DA device, you need to configure:
- OPC XML-DA Server(s) to specify the servers on which data is to be scanned, along with any access and security settings required to communicate with those servers.
You need to configure one OPC XML-DA Server item in the database for each server with which you want to communicate using the OPC XML-DA protocol (see Configuring an OPC XML-DA Server).
- OPC XML-DA Scanner(s) to specify which nodes are to be scanned and the rates at which the data is to be retrieved.
You need to configure a minimum of one OPC XML-DA Scanner per OPC XML-DA Server. You can attach multiple scanners to the same server. For instance, you might configure different scanner to have different scan rates or offsets, in order to retrieve some data at different intervals or times to other data.
For more information, see Configuring an OPC XML-DA Scanner.
- OPC XML-DA Points to represent the measuring instruments and control devices on the servers that are communicating using the OPC XML-DA protocol.
For more information, see Points Used on OPX XML-DA Scanners.
To minimize the time that it takes to configure the required OPC XML-DA items, you may want to configure them in the order listed above, as the scanner configuration requires that you specify a server, and point configuration requires that you specify a scanner, and so on.