From FAQ

"Are the IBDAC connection components thread-safe?

Yes, IBDAC is thread-safe but there is a restriction. The same TIBCConnection object cannot be used in several threads. So if you have a multithreaded application, you should have a TIBCConnection object for each thread that uses IBDAC."

What does it exactly mean? Do I have to create new TIBCConnection every time I start new thread or I can use same TIBCConnection in multiple threads but not at the same time? For example, can I create TIBCConnection in main thread, start another thread, pass it connection, use connection in thread, finish thread, start another thread, pass it the same connection, use it in thread, finish thread, and so on without closing connection?

I tried using one TIBCConnection from in main thread and in other threads at the same time and it worked.