The way I do this is to have a class that runs the seedlink client, and a method on that class that allows you to access the data in another thread. If you want to see an example of how I implement acquisition and subsequent plotting and processing of real-time data then check out RT-EQcorrscan - in particular, the Streamer abstract base-class implements the methods I mentioned. It has a lot of additional things that you probably don’t need, but the key things are the
get_stream method and associated locks and buffers. It is worth pointing out that as soon as you get into multi-threaded programming locks become important, and life gets a lot more complicated!
I can’t help with any more specific details without seeing some code and understanding what you are trying to do. If you are just trying to plot data from a seedlink client then this project might be appropriate, but it hasn’t been updated for a while.