using python 2.7 and library OpenOPC using read or write function explode

Question

I use python 2.7 & OpenOPC to communicate with OPC servers. I have 2 different servers. With one server everything is Ok.

I can:
- connect and get information from the server
- get list of objects
- get properties of objects
- read value of items
- write values. If a value is not autorized for writing, an error is get from the OpenOPC library and I can manage it with the python code

On the other server, it crashes:
- everything is working like the first server but
- when I try to read or write, the python code explode

With this server, if I use the opc.exe in the command line, it also explode when write or read. For example:
- opc -s Als1.s8000.1 -i connect the server and let me see the properties
- opc -s Als1.s8000.1 -l L4A1 list all the sub items under L4A1
- opc -s Als1.s8000.1 -r L4A1.LPSLOOP1C01.RM02 -> generate a popup "opc.exe has stopped working bla bla bla"

Thanks in advance for your help

Answer 1

Some progress about this question.

We tried to use some trace to see what is managed by the server. Curiously when I use OPCInspector, an application able to communicate with the OPCservers, we are able to read and write... But the logs show us OPCInspector does not use the same function to do that as OpenOPC.

So next step is to add some traces in the server side to understand what happens in the Alstom server. I mean, it smells this is not an OpenOPC question but the server question.

Answer 2

Well, I found where is the problem. The Alstom OPCServer is managing the OPC request in his way. I've seen the c++ code from the server and I managed to modify the python OpenOPC library to send correct arguments to the Alstom server.

Thanks for your help and the positive evaluation of my question.