High Performance OPC Server
KEPServerEX is the latest generation of KEPware's OPC server technology. Building upon the original KEPserver, KEPServerEX has incorporated many of the features requested by KEPware's customers. In addition to customer driven enhancements, many technological changes have occurred. These features and enhancements have all been made with the goal of providing an OPC server that demonstrates unparalleled compatibility and performance.
A few of the enhancements are transparent to the user, but there are a number of new features that are readily apparent and directly available to the user. The following sections will describe the primary features of KEPServerEX.
KEPServerEX has been enhanced to provide the widest range of connectivity of any server product available. KEPServerEX supports the following client server technologies:
OPC Data Access 1.0a was the original specification the OPC Foundation developed back in 1996. Many of the OPC client applications in use today support this original specification. OPC Data Access 2.0 is the latest version of the OPC interface. The 2.0 version of the interface has been enhanced to make better use of the underlying Microsoft COM technology. Most OPC client applications are being converted to support version 2.0 of the OPC specification. The DDE formats CF_Text and XL_Table are the standard DDE formats as defined by Microsoft. All DDE-aware applications support the CF_Text format. The XL_Table format is primarily used within Microsoft Excel to allow it to gather DDE data in an array format that can fill multiple cells in a spread sheet. XL_Table can be used to move data into an Excel spreadsheet with a little more efficiency than standard CF_Text. AdvancedDDE is a variation on the normal CF_Text format. Advanced DDE allows larger amounts of data to transferred between applications at higher rates of speed, and with better error handling than a normal CF_Text DDE link. In keeping with KEPware's goal of providing the broadest range of connectivity, KEPServerEX simultaneously supports all of the client server technologies listed above. Client applications using any of these technologies can access data from KEPServerEX at the same time.
Based on Microsoft's COM technology, OPC servers can share data with remote client applications using DCOM(Distributed COM). DCOM allows you to use a single OPC server to provide data to client applications running both locally and on remote machines. DDE is not without its own means of allowing remote access. All of the DDE formats supported by KEPServerEX can also be accessed remotely using what is known as NETDDE. NETDDE allows a remote DDE client application to use the machine name of a remote DDE server when specifying a DDE link. KEPServerEX has been designed to allow both of these methods of remote server access. In terms of OPC connections, KEPServerEX will properly configure your DCOM settings to allow remote OPC clients to access and browse KEPServerEX. For DDE clients, KEPServerEX will automatically start NETDDE services and register all of the required DDE shares to allow remote DDE clients to access device data. Establishing DDE share names can be a time consuming process with this in mind, NETDDE services are not enabled in KEPServerEX by default.
KEPServerEX is somewhat unique in its approach to providing OPC connectivity for a number of devices. In most cases OPC servers are written as single function programs that can handle only a single device type or protocol at a time. The result is that multiple OPC servers are required to handle a range of devices and protocols. KEPServerEX is written as two separate components. The server component houses all of the user interface and OPC technology. Device specific drivers plug into this server component. If only one communications driver could be plugged into the server at a time then we would have gained nothing. KEPServerEX allows you to use a number of communications drivers concurrently. Click here to find out what plug-in communications drivers are available for KEPServerEX.
Runs as NT Service
KEPServerEX supports running as a service under Windows NT/2000. Service operation is completely user configurable from the Tools|Options menu and can be changed at any time allowing you to move from normal stand alone program operation to NT service mode. Running as an NT service is crucial for many applications where KEPServerEX is providing data to OPC clients via DCOM. For these applications a loss of DCOM connection can not be tolerated. Normally an OPC server that only supports stand alone program operation is forced to shut down when it's host machine experiences a user log in or log out. While running as a service, KEPServerEX can continue to supply OPC data across user log in sessions. While running as a service KEPServerEX can be configured to interact with the desktop allowing you to make changes to your KEPServerEX project. It can also be configured to have to NO visible presence while running.
KEPServerEX now supports direct scaling of device data. Scaling allows raw device data to be converted to engineering units for OPC client applications. KEPServerEX provides a number of unique scaling features that make it easy to implement scaling in your application
The Scaling in KEPServerEX supports Linear and Square Root formulas. You can specify the range of the raw data from your device and the engineering range of the scaled value. In some cases the raw data received from a device may exceed the range set for the raw data. If this occurs the engineering value can be forced outside of the range you desire. To prevent this, KEPServerEX allows you to specify that the scaled value be clamped to the engineering ranges. In most cases it is always assumed that a scaled value results in a floating point number. KEPServerEX doesn't make this assumption and allows you to select the scaled engineering value to be any valid OPC data type. This means you can scale a 16 bit integer value to a 32 bit integer value. "Double" is the default data type for all scaled values. To make scaling complete, KEPServerEX allows you to specify the units for the scaled tag. A string of up to 32 characters can be entered and attached to the tag. If the OPC client application in use supports access to OPC tag properties, the data ranges and the units can be used in the OPC client to automatically configure objects like user input or data displays.
On-Line Full Time
On-line KEPServerEX is on-line all the time. To acquire data from a PLC or device, a channel and device must be configured in the server, and a client application must be requesting data. The full time on-line mode of operation allows a KEPServerEX project to be modified while the server continues to supply data to client applications. Almost every parameter can be changed while the server is operating. Parameters like communication port or baud rate can be changed while a client application is active, if needed. More importantly, user defined tags can be added to the server without shutting down client applications. When new tags are added to the server, they are immediately added to the OPC browse space, and will be available to OPC clients.
With a powerful feature like on-line full time operation, managing what your users can do in your OPC application becomes a necessity. KEPServerEX includes a built-in User Manager that allows complete control over what types of functionality each individual user can access. The default administrator account allows you to add multiple users, each with their own set of rights for server access. Any user action that can influence or disrupt server operation is logged to KEPServerEX's event logging system. By default, all server operations are available at all times. The User Manager functions of KEPServerEX are available only if you need them.
KEPServerEX's new user defined tag management features allow you to create a tag database structure that fits the nature of your application. Multiple tag groups can be defined to segregate your tag data on a device by device basis. Drag and drop editing makes adding large numbers of tags easy. Additionally, CSV import and export allows tag editing to be done in any application you desire. Like all other features in KEPServerEX, new tags can be added to your application at any time.
KEPServerEX's new diagnostic features provide real-time data on the performance of your communication driver. All read and write operations can be viewed in the diagnostic display window of KEPServerEX or can be tracked directly in your OPC client application by using its built-in diagnostic tags. These diagnostics make it easy to debug really tough communication issues. The diagnostic display window also provides a real-time protocol view. Given that KEPServerEX is on-line full time, you can view the real-time protocol window while you make changes to key communications parameters like baud rate, parity, or device IDs. As you make changes to your communications parameters you'll see the effect on communications in real-time, and once you set the correct communication and device settings, you'll immediately see the exchange of data with your device.
KEPServerEX supports the use of modems on all serial communication drivers. Modem control is provided by a set of new modem tags. Once modem operation is enabled for a KEPServerEX project, a predefined set of modem tags becomes available to client applications. The modem tags provide control of dial, dial number, hang up, and auto answer mode. Additional modem tags provide status of the modem connection. Using these modem tags, client applications can be designed to control all aspects of a modem connection. KEPServerEX's modem support allows you to extend your system management and data gathering needs beyond the control room.
OPC Quick Client
KEPServerEX includes an extensive OPC Quick Client application to aid in the development of your OPC applications. The OPC Quick client has multiple built-in test modes that will exercise your KEPServerEX application. Comprehensive error reporting helps diagnose common OPC Client/Server issues.
Visual Basic Examples
goal is to make using OPC technology easier regardless of the type of
OPC client application you may be using. For many of your applications,
Microsoft's Visual Basic provides an ideal environment to create custom
industrial applications. Until now, using OPC technology in your Visual
Basic application might have left you with more questions than answers.
The simple and complex VB examples included with KEPServerEX are well
commented and provide additional pointers for using OPC servers in your
VB applications. The complex OPC example implements a complete OPC test
client in VB with the ability to handle multiple OPC servers, multiple
OPC groups, and multiple OPC tags. No example of OPC technology would
be complete without OPC tag browsing and the complex example gives you
a complete tag browsing interface. All of the source code for these examples
is provided in the KEPServerEX download.
KEPServerEX has been designed to place as little stress on your system as possible while still providing the level of performance you expect. We recommend the following system requirements:
Notes: While KEPServerEX will run on Windows 95 and Windows 98 we strongly recommend the use of either Windows NT 4.0 SP5 or Windows 2000 for use in industrial applications. Windows NT and 2000 are not only more robust, they also provide a 5 to 10 fold increase in OPC Client/Server performance over Windows 95/98. Windows NT and 2000 also have better handling of serial communications ports and ethernet sockets. To learn more about the benefits of Windows NT and Windows 2000 please visit Microsoft.