OPC is an acronym for OLE for Process Control. It is an industry standard introduced by Microsoft based on DCOM. If there is not a “Genuine WebAccess Driver” for your automation device, then you should see if the manufacturer (or a 3rd Party like Kepware) supplies an OPC Server for the device. WebAccess can be both an OPC Client and as an OPC Server.
WebAccess is an OPC Server. The tags in WebAccess can by browsed by an OPC Browser and read by other OPC Clients. The name is Broadwin.BWOPCServerDA.1.
All the IO Tags and Blocks are available. As long as the Kernel is running. Also, if there are multiple projects downloaded to the SCADA node, only the tags in the Project that is running will be available. The OPC server (BwOPCServer.exe) will connect on request any time regardless whether Datacore.exe is running or not. If Datacore.exe is not running, the WebAccess OPC server will still connect but all the values for the valid tags will be returned as bad values.
The BwOpcServer.ini, used in earlier versions, is no longer needed when the SCADA node acts as an OPC server.
The WebAccess OPC Device driver is an OPC Client. Hardware manufactures typically supply an OPC Server to provide access to real-time data. Most OPC Servers allow tags to be "browsed" and "imported". WebAccess provides an OPCTool.exe that allows tags to be "imported" after you have configured an OPC Comport and at least one OPC Device.
WebAccess OPC client supports OPC 2.0 and 3.0.
The third-party OPC Server software is usually is installed on the SCADA node (a Local OPC Server).
The OPC Server software can also be installed on another PC (a Remote OPC Server) that is not the SCADA Node. A TCP/IP network connection (usually a LAN or Intranet) is used to communicate to the "remote" OPC Server from the SCADA Node. The remote OPC Server must have either WebAccess Project Node software or OPC Service installed. WebAccess provides a set of pre-built communication “drivers” that enable engineers and technicians to easily establish communications to automation devices including PLCs, controllers, DCS, DDC systems, other software packages, recorders, RTUs, IO, smart transmitters and other automation hardware.
The steps to configure the OPC driver are:
1. Start Internet Explorer Web Browser.
2. Enter IP address of the Project Node.
3. Use WebAccess Configuration.
4. Open or Create a Project.
5. Configure a SCADA node (the PC that will connect to the automation hardware).
6. Configure a Comport for the SCADA Node that is an OPC type Comport. Assign an OPC Server to this Comport.
7. Configure an OPC Device (determines the communications Protocol or Device Driver).
8. Start the OPCtool.exe on the Project Node.
9. Import Tags using the OPC Tool, Import/Add Tags and the Browse feature.
10. Optionally apply Tag name conversion rules before importing tags.
11. Edit Tags in Project Manager to assign Alarms, Scaling, Engineering Units, Description and other features.
There are drawbacks to using an OPC Server:
· You must maintain two (2) communications databases, the OPC tag configuration and the Web Access Tag configuration. If you change the Tag name in OPC Server, you must change the OPC Tag address in WebAccess to match the new name.
· Technicians must translate the OPC Tag name to the device address when troubleshooting or identifying IO.
· Most OPC Servers do not support remote configuration. Most OPC Servers require configuration to be performed locally on the OPC Server Node (usually the SCADA Node).
· In version 4.0, the WebAccess OPC Tool (the Import Tool) must be run locally on the Project Node.
· The OPC Software is a second set of software programs that must be maintained and monitored.
Generally, it is best to use a WebAccess Driver specific for your device, instead of OPC, when considering remote configuration.