Hello to all of you. I am currently writing my bachelor thesis on evaluating the performance of OPCUA Subscriptions and OPCUA PubSub. I am using open62541 for the implementation so I am not sure if this is the right forum to ask this but here it goes.

The setup will consist of three Raspberry Pi’s. One is hosting the server, one is running the client and the third is supposed to measure the timing delays as an independent clock. Right now I am simulating this on a local machine so everything is running on the same system. For the subscriptions I am using the server timestamps and then on clientside calculating the delay with UA_DateTime_now(). But I am afraid this will not work when client and server run on two different machines.

And now for the even bigger problem: I dont know how to measure the delays for PubSub even if Publisher and Subscriber are running on the same system. I have a callback in place for the TargetVariableNode but calculating this with the UA_DateTim_now() just yields a negative time and it does not change at all so it cant be valid.

Now my questoin is how would you go about measuring Subscription performance on two different systems? My idea was to use the GPIO pins and hardwire them to measure timing. But the question remains when to toggle them as there is no callback on the serverside ob subscriptions that gets called everytime you sample. Or is there? I dont know.

The other question is how to measure PubSub performance at all. On the same system or two different system I unfortunately have no clue how to about that. If you have any keywords for me to research or even example code I would be very greatful.

If you need more information or code please ask me.