Liaison OPC DA : Introduction 🔒
OPC Data Access (DA) only deals with real-time data, using the follwoing attributes:
a value, the quality of the value and a timestamp.
These three attributes have to be returned to an OPC client (ALERTs OPC DA connector) making a request (advice or polled) to an OPC DA Server, see schema below.
According to the picture above, ALERT acts as an OPC DA client to manage the data of an OPC server.
You will find the settings for the type of request in the OPC DA data server properties later in the OPC DA Client settings part.
Remark: The OPC DA specification is using the Microsoft COM technology. That means, if the OPC server is located on a remote machine in a TCP/IP network, the complex configuration of the DCOM settings is required. In this case we suggest to use the ALERT OPC DA Tunneler ALERT OPC DA Tunneler or another tunneler software of a third party vendor.
