The easiest way to establish a connection to the TNC from a directly connected PC is with TNCremo/TNCserver.
If the TNC control already has a network card (iTNC 530 or higher), then at least one IP address must be provided. Please refer to the description in the User’s Manual, because the procedure varies slightly based on the NC software.
All of the TNC controls also feature an RS-232 interface (Recommended Standard 232). But due to its very limited capabilities and speed, this interface should be used only on older models.