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9.3 PROFIBUS DP Overview PROFIBUS DP is a master/slave, token passing network, which utilizes a request/response protocol. Basic data exchange operations ensure that on a periodic basis, the master sends an output message to each slave, which responds in turn with an input message. PROFIBUS DP is typically used as an I/O network. As compared to a traditional I/O network architecture that requires dedicated wiring between each I/O module and the controller device, PROFIBUS offers the advantage of a single network/bus on which all I/O peripheral devices reside. Fiber Optic Since the physical interface to Experion currently employs an electrical connection, the use of fiber optic media will not be discussed in this document. It is expected however that various commercially available products can be used with the Experion system, which will allow the use of electrical, as well as fiber optic media on a PROFIBUS DP network. Bus Wiring (electrical) PROFIBUS DP utilizes a “daisy-chain” bus topology, with a single PROFIBUS cable wired from the master to the first slave and through each slave in the network. “Branches” can be supported through the use of segments, isolated by repeaters, which are described briefly below. The electrical wiring media used for PROFIBUS is a shielded twisted pair (2 conductors plus the shield). Specialized cable that meets the PROFIBUS application is commercially available. The connectors used are typically a 9 pin Sub-D connector, with pins 3 and 8 used for the positive/negative data signals. Refer to wiring diagrams for the equipment in use for additional details. The devices at the ends of each segment require active termination, the circuitry for which is generally specified on a perdevice basis. Alternatively, PROFIBUS connectors with an integrated termination circuit are commercially available. Refer to the device technical documentation for additional details on wiring and termination. Device Profiles Due to the lack of definition at the presentation layer, the PROFIBUS Trade Organization (PTO) has defined a set of device profiles that provide some level of standardization for certain complex devices. These profiles are not formally a part of the PROFIBUS protocol definition, so they are not considered a part of the PROFIBUS communication model depicted above. However, for certain devices these device profiles provide some degree of standardization at the data management layer. Note that device vendors are not required to utilize these profiles. The set of available profiles include the following:  Profile for communication between controllers  Profile for process control devices  Profile for NC/RC controllers (robotics)  Profile for variable speed drives  Profile for Encoders  Profile for HMI systems  Profile for safety