Unified Automation Forum

Dear Support Team,

I am using Ua Gateway to connect an OPC DA Server from CoDeSys to an OPC UA Server. I am using the Ua Gateway and connection could be established.

However when I connect the Ua Expert, when I choose the tags from the nodes I cannot visualize any real time data, although in the Attributes (right side of the Expert), I could retrieve a value from the last timestamp before I browse in the Address Space.

To clarify, from a tag DI0,in the Data View Access there is no Value and a Null DataType, while in the Attributes I could retrieve a value "false" from 05/01/2023 19:03:11.501 for example, but there is no update.

Furthermore, there are some OPC DA clients tha I am using to visualize data and I could establish connection and get real time data.

Actually, I have no background experience with OPC in general in case I have made any easy questions. I would appreciate any reply.

Hi,

the CoDeSys Server >= version 3 supports to run as a service, which is the better option in combination with UaGateay (which runs as a service as well). Make sure the CoDeSys runs as a service !

Background: the Attribute-Window in UaExpert is doing an explicite "Read" on the individual attributes (including the value attribute) of the selected tag. This is fundamentally different than the DA-View. The DA-View is doing a "monitoring" of the tag (Subscription, CreateMonitoredItem, Publish). If the DA-View is not showing any values (empty, Null datatype), there was no (never) any value received for this tag. Most typical reason is that the data source (in this case the CodeSys-Server) has never sent any DataChange for this item. There might be two possible reasons for this issue: Either the data source (in this case the CoDeSys-Server) is disconnected from the underlying PLC data source (PLC has no data, is not running, Tags not configured correctly), OR it has data, but can not send the DataChange notification to the UaGateway (CodeSys must run as a service).