Distributed Component Object Model (DCOM) calls may take a long time to time out if the network is down, or if the server is unavailable. The actual DCOM timeout depends on a number of factors, including which network protocol DCOM is using and whether the server or network went down before or during the call. In some cases the timeout may be up to 6 minutes. DCOM makes use of RPC, and although RPC does allow some amount of control over call timeout, the programmer cannot normally take advantage of it because DCOM does not give access to the underlying RPC binding handle.
Industrial automation typically requires quicker recognition of a communication problem, and faster remedial actions. Clever OPC clients may overcome DCOM limitations by using special techniques.