NEMA NTCIP 2102:2003

This standard is applicable to transportation related devices that must operate in a typical primary/secondary configuration where one device is the designated primary while one or more other devices are connected to one channel acting as secondaries. As a subnetwork profile, it specifies a set of protocols and standards applicable to the data link and physical layers of the OSI Basic Reference Model. The SP-PMPP/FSK is intended to provide an interoperability standard for the Physical and Data Link Layer aspects of communications in transportation related devices. The primary purpose of this standard is to provide a simple data exchange tool that uses a connectionless delivery mechanism. This subnetwork profile lists the requirements for an implementation using an unbalanced mode of operation for the data link layer that have been derived from the High-Level Data Link Control (HDLC) standard. This subnetwork profile defines not only the definition of the physical and the data link layer protocols but also the interface definition between the data link layer and higher layer protocols.