OPC Node

OPC Node

The Rayven OPC node uses the OPC UA protocol to request data from remote PLCs via an OPC UA server. It does this over an IP connection.

The OPC node will request updates for designated signal fields at the specified rate and add returned values to the JSON object under a new field name.

About OPC UA

OPC Unified Architecture (OPC UA) is a cross-platform, open-source, IEC62541 standard for data exchange. It replaces OPC Data Access (OPC DA), which only communicates real-time data (not historical data, alarms, or events). In contrast, OPC UA has three specifications: 

• Data Access performs the classic exchange of current data. A value can be read and written for each data point. A data point value contains the actual value, the time stamp at which it was current, and the value quality (result validity).
• Historical Access allows the querying of historical values where the server has the internal data memory required. A client that reads historical data points via Historical Access also transfers the desired time span to the server in addition to the data point information. The Rayven OPC Node doesn't currently support this format. 
• Alarms and Conditions enable a standardized model for alarm messages and alarm logic. For OPC client applications standardization simplifies the generation of alarms from data point values, as the OPC server can implement logic instead of the client software manufacturer. The Rayven OPC Node doesn't support this format. 

Configuring Device IP addresses

Before setting up the OPC node, you should have at least one device configured with an IP address. You can configure these in the device list under device management. To set the port, add a colon and the port to the end of the address. For example, 'mydomain.com:135'. For more information, see Device Management. 

Adding an OPC node to your workflow

1. First, select your desired solution from within Rayven Workflow.
2. Select ‘Inputs’ from the left-hand panel.
3. Find the OPC node and drag it onto the canvas.
4. Double-click on the OPC node to open its configuration window. 

Configuring your OPC node

1. Give your node a name. Choose something simple that clearly explains the node’s purpose. You must pick a name that has three or more characters.
2. Define the interval between requests to the designated IP address using the Update Rate field. This value is measured in minutes. For example, entering '5' will result in a request every 5 minutes.
3. Choose whether to enter a username. If setting a username, it needs to be the same as the one in the OPC server.
4. Choose whether to set a password. If used, this needs to match the password set in the OPC server. 
5. Enter the signal name as received from the OPC server. You must identify at least one OPC signal to read and can add additional signals by clicking on the ⊕ Add Value button. The OPC node will make requests at the specified update rate for the designated signal fields.
6. Add a value signifier for transferred PLC data under 'Field Name'. Each OPC signal field will be returned under this name and added to the JSON object.
7. Select the appropriate Device Filter. For more information, see Device Filters.
8. Click save and then the 'activate' button. You have now configured your OPC node.