Hi,

We have a follow up question regarding setting the MaximumAge property in VBA. Is it possible to set this property globally, so that we can use the simple ReadValue method instead of more cumbersome setting of the UAReadArguments?

In general what is the best way to read values in VBA directly from device (not from cache)?

Best regards,
Miha

Hi,

thank you for your fast reply. My colleague tested implementation of application with your suggestion and it works properly, the read values are now the latest values.

So after additional testing we have come to the following conclusion. If there is an active connection, establish by some other OPC UA Client such as OPC Scout, UAExpert, Traeger OPC UA Client etc. which don't use connectionless approach (need to call connect method before being able to read and write), SIMATIC NET OPC UA Server data is refreshed promptly and we receiv the expevted values fro mthe server when readin with QuickOPC UA Client. If there is no connection establieshed, read value is wrong (last old value read by the server when there was some kind of connection established).

Is there a way for QuickOPC UA Client to establish an active connection to the OPC UA Server? I think this would solve the issues we are currently facing.

Hi,

Client 1 is GE Ifix which is reading and writting values from / to OPC UA Server via QuickOPC for COM.

Client 2 is our .Net Core application which is reading ang writting values from / to OPC UA Server via QuickOPC for .Net Core.

We have performed another test today using SIMATIC NET. We have subscribed to all parameters on the OPC UA server and are checking the trigger variables based on a timer every 500 ms. OPC UA client writes the data to the OPC UA Server sequentially in a manner "Username", "Password", "trigger". Once the trigger value is changed, our application detects the trigger and starts handling the received data. Once the operation is finished a response from our application is written to the trigger location. In the next time cycle this same trigger, to which we have written the reponse, detects a value (old value) which again triggers the function but it shouldn't becase the trigger value was overwritten by the application in the previous time cycle.

Time cycle 1:
1. Client 1 writes username to server
2. Client 1 writes password to server
3. Client 1 writes trigger to server (value 1)
4. Client 2 detects the trigger in its current time cycle
5. Client 2 handles the received data
6. Client 2 writes a response to the trigger location (value 2)

Time cycle 2:
1. Client 2 reads the trigger location
2. Client 2 reads value 1 from the trigger location (it should read value 2)
3. Client 2 handles received data again (data from the allready handled trigger)
4....

Time cycle 3:
1. Client 2 reads the trigger location
2. Client 2 reads value 2 from the trigger location (this value was written by Client 2 in Time cycle 1)
3. ....

To tell things short, subscribing to a variable didn't resolve the issue of receiving old data from the OPC UA server. Any suggestions how to solve this?

Looks like QuickReply didn't work.

CompletesAsynchronously is se to false.

We have conducted a test Where OPC SCout was on client and the second one was UAExpert. We have written the value with UAExpert to the PLC and the read value by OPC Scout was correct.

If we execute the code from my original post the read value is the old value, wrong value. QuickOPC only gets the correct value if either OPC Scout Monitoring is active or monitoring in UAExpert is active, meaning when connection to the OPC server is established.

Is there a way to open and maintain connection to the OPC UA server by QuickOPC UA client? Apart from subscribing to desired variables.