OPC Anywhere

If you don't want to be bothered by DCOM, you should take a look at this, which is a no DCOM/no hassle solution. Good luck!

It is very hard to figure out from this limited info. I would suggest trying this solution, which supports Python natively without dependency on any 3rd party OPC library. No DCOM, no hassle. Cheers!

Others reported similar issues in using this very old Python library. That is why you can give this new way a shot for recent Python release.

That could be caused by DCOM setting for that specific OPC Server, which could block your client connection until time out. To avoid this kind of headache, you can give a try here, which doesn't use DCOM at all. You can have a quick smoke test by using it. Cheers!

To avoid this kind of headache, check WebSocet4OPC, which can behave as a Gateway as needed. No DCOM is involved and it retrieves back OPC data in JSON format across different platforms. It can be used with recent Python release like version 3.9/4.0 etc. It also supports DA/AE/HDA.

0x800706BA means The RPC server is unavailable. Typically, that means you need do some DCOM configuration in remote box. To avoid this kind of headache, you can take a look at WebSocket4OPC, which brings back OPC data without any DCOM configuration. It supports Python and other popular languages to return OPC data in JSON format.

There is an A&E support at WebSocket4OPC. It has various clients to support. Actually, you can use Python to retrieve plant data from any OPC DA/AE/HDA servers. It has JSON return so easy to parse. Cheers!

Sebastian / Vidar - Thank you both for your input! I made progress with your help. I have noticed one thing related to GlobalFree(handle) as the last line of code. If I put this line there is a heap currption as stack shown below. It works without that line, but would this cause memory leak? I check online somebody else having the same issue. Any idea? Thanks! ntdll.dll!77dd61a7() Unknown Non-user code. Cannot find or open the PDB file. [Frames below may be incorrect and/or missing, no symbols loaded...