Abstract: The present invention relates to an interface for a maintenance system used in conjunction with a process instrumentation system. More specifically, the invention relates to an interface used for maintaining and configuring smart devices. Even more specifically, the invention relates to an interface that may safely be used to maintain and configure smart devices where such smart devices are located in hazardous areas. The interface, which may be removably mounted to a termination board, has a control section, a port replacement section, a permanent storage section, a temporary storage section, an address/data bus, a UART, a standard clock pulse generation device, an option select device, a modem, a channel selection decoder, a wave shaping device, and at least one multiplexer. The interface and a termination board for use in process instrumentation systems that require intrinsic safety are explained by themselves and in system and function contexts.