Hands-On Industrial Internet of Things

The OPC UA data exchange

The easiest way to exchange data between an OPC UA client and a server is to use read and write services. The read and write services are optimized to transfer a bunch of data rather than single piece of data or a few values. They allow us to read and write either values ​​or attributes of nodes. The read service has the following parameters:

• maxAge: This is the maximum time taken for the values to be returned. It is specified by the client. It forces the server to access the device (for example, a sensor) if the copy in its cache is older than the maxAge parameter configured by the client. If maxAge is set to zero, the server must supply the current value by always reading it directly from the device.
• Type of timestamps ...