You know you already need OPC Client capabilities in your existing/new application. You also know that you do not have the time to learn the OPC Specifications that other 3rd party controls require you to do. You need a tool that's tried and tested and has a proven track-record. You need a tool that is going to continue working 24x7x365. You need a tool that can trap errors, handle them gracefully and give you this information so that you can handle them gracefull in your application. The OPC Data Control ActiveX delivers this because of its intelligent back-end engine that actually handles all of the complexities of OPC for you, which leaves you time to focus on the development of your software. Simply drop an instance of the OPC Data Control ActiveX onto your form, and then you are ready to create OPC Client based applications, maybe without writing a single line of code -- click here to see how. The OPC Data Control will establish and maintain the connection to your OPC Server. The OPC Data Control will also gracefully disconnect from the OPC Server, cleaning-up after itself upon request too. Because you are in control, you can read/write to data at will... in fact, there are several ways in which you can read data. Binding: You can setup a relationship between a Tag in the OPC Server, and a textbox (or any COM-based control) on your form. The OPC Data Control will automatically keep the data in the Textbox up to date, likewise, when the textbox value changes as a result of the end-user then the OPC Data Control will automatically write that value back to the OPC Server. See ConnectName, ConnectObject and Binding in the Source section. Subscriptions: Otherwise known as exception-based reads. You simply specify the Tags you want the OPC Server to poll, and then you wait for "ValueChanged" events to fire to notify you when a Tag's value has changed.    See ConnectName and ConnectObject in the Source section. Manual Reads: You also have the ability to Read a Tag, or a number of Tags within a single transaction, any time!  See ReadVariable and ReadMultiVariables in the Source section. Writes: You can write a tag, or a number of tags in a single transaction, at any time. You get instant notification as to whether or not each tag-write was a success or not.  See WriteVariable and WriteMultiVariables in the Source section. Need more control? You can connect and disconnect to/from an OPC Server at any time. You can enable and disable Tag Subscriptions at any time. You can build dynamic applications that are based on external configuration files to specify the name/location of the OPC Server, the Tags to subscribe to and also the Objects to bind Tags to, if applicable. Even though the OPC Data Control does all of the OPC "grunt work" for you, you still have control over the data and when it gets read and written. Any errors are reported to you. The OPC Data Control not only returns error codes, but also has the ability to simply display them on-screen as well as the ability for you to programmatically translate an error code into a human-readable error-description. Once your application is built - deploy it!