Does OPC Expert support two-way OPC communication, including writing data values and commands from the client to the OPC server?
Sending Data and Commands from OPC Client to OPC Server
OPC Expert supports bidirectional OPC communication. In addition to reading data from OPC servers, it can write values and commands back to OPC server items, making it useful for scenarios where a client application needs to send setpoints, acknowledge alarms, or trigger actions on a connected device. This write capability is present across the supported OPC protocols including OPC DA and OPC UA.
Writing Data Through the OPC Viewer
Within the OPC Viewer module, subscribed items that are defined as writable by the OPC server can be written to directly from the OPC Expert interface. This is used during commissioning and troubleshooting to verify that write paths are functioning correctly, and it provides a quick mechanism for manually adjusting setpoints or resetting values during testing. The write operation behaves according to the permissions defined on the OPC server, so items marked read-only by the server cannot be overwritten from the client regardless of what the client requests.
Writing Through the REST API
OPC Expert’s REST API exposes write functionality over HTTP, enabling any application that can make a web request to send values to OPC server items. This is the mechanism used when Python scripts, web applications, or other non-OPC-native systems need to push data into an OPC-connected device. The REST API accepts data in JSON format, making integration straightforward for developers working in any programming language.
Writing Through OPC to Excel
The OPC to Excel module also supports writing values back to OPC server items directly from a spreadsheet. A value entered in Excel can be pushed to a connected OPC server item, enabling Excel-based operator interfaces or test sheets where a technician can write setpoints without leaving the spreadsheet environment.
Relevant Tools
OPC Expert (OPC Viewer): Provides a direct interface for writing values to OPC server items during commissioning and troubleshooting.
OPC Expert REST API: Exposes write operations over HTTP for integration with external applications and custom client development.
OPC Expert (OPC to Excel): Supports writing values from Excel cells back to OPC server items, extending Excel’s role beyond data display into interactive control.
OPC Expert treats read and write as equally supported operations across its modules, giving engineers and integrators a consistent mechanism for both monitoring process data and interacting with connected systems.