Our software can communicate over COM with Excel. An example is that Excel calls a COM function which causes our software to respond with results. However, if it takes our software more than around 3 minutes to calculate those results then the COM reference is dropped for some reason.
Is this just the nature of COM (to timeout if it doesn’t receive a response to a call after a certain time) or are we doing something wrong?
COM doesn’t have in-call timeout. If you start a call and the server enters an infinite loop while handling it the call lasts forever unless there’s a communication problem between the client and the COM server.
However there’re timeouts for network connection problems. With the symptoms you describe it looks like some communication problem.