Design And Development Of Redundancy Protocol Converter Between PROFIBUS-DP And MODBUS

PROFIBUS-DP and MODBUS fieldbus are widely used in industrial control field, but the MODBUS protocol and PROFIBUS-DP protocol are heterogeneous, not only cannot be connected directly, and the configuration is very complex, very inflexible to use.This thesis designed a redundant structure protocol converter between PROFIBUS-DP and MODBUS, it supports dual-redundant PROFIBUS-DP link, and supports dual-converter and active-standby switch redundancy. The protocol converter play a part of slave station in PROFIBUS-DP fieldbus, master station in MODBUS fieldbus. This converter support polling 60 MODBUS slave stations at most, it’s data length of input or output can up to 1920 bytes.it supports frame format of MODBUS RTU and MODBUS ASCII and 8 species(01, 02, 03, 04, 05, 06, 15, 16) MODBUS standard function code, it’s configuration is simple, using flexibly.Protocol converter adopted two ARM Cortex?-M3 chips to realize respectively the PROFIBUS-DP slave station and MODBUS master station’s function, adopted Xilinx XC6SLX9 chip to realize two protocol mutual mapping, redundant device switch, monitor hardware fault and other functions. In addition, the design of communication interface adopted capacitive coupler + driver chip’s designed approach, the external signal interface design adopted optical coupler, anti-ESD, against lightning surge designed method in order to improve the reliability.Firmware design of protocol converter started from PROFIBUS-DP and MODBUS fieldbus communication protocol, frame structure, the structure of the system, the OSI communication model, researched the key technology of protocol mapping relationship, multiple frame transmission, data integrity, given design plan supporting redundancy and double direct protocol converting, achieved firmware design of protocol converter between PROFIBUS-DP and MODBUS.Finally, this thesis set up the debugging and testing platform based on the practice unit’s DCS system. It verified the correctness of this thesis design through debugging and testing.