Research And Realization Of Time Synchronization Protocol In Distributed Control Systems

With the development of the Ethernet, the technology used in the industrial field will beunstoppable, but the instantaneity among the every control station of DCS can’t be ensuredbecause the influence of medium’s delay and the protocol stack’s running, which greatlyblock it’s development in fields such as industrial automations and control、communication、measuring field and so on. These are the inherent problems of DCS itself, itis difficult to solve by their existing technology. If every node of DCS can realize the timesynchronization, the DCS will work more efficient, the IEEE1588protocol’s (precision timesynchronization protocol for network measurement and control system) emergence solve theproblem well. The IEEE1588standard defines a Precision Time Protocol (PTP) for real-timesynchronization, can achieve time synchronization as submicrosecond level for many nodes.This paper gave a deep introduction about the reason which lead the nodes such as everycontrol station and I/O template of DCS are out of synchronization， introduced thedevelopment and application situation of time synchronization technology, especially thetime synchronization technology which applied in network synchronization and comparethem，demonstrated the IEEE1588protocol has the highest accuracy now,is the best timesynchronization standard which suit the DCS. Then did detailed research and descriptionabout some key technology about IEEE1588protocol， including the PTP protocolspecification、formate of the PTP message、mechanism of time synchronization、modules oftime synchronization the best master clock algorithm and so on.This paper studied the method of using IEEE1588protocol to solve the timesynchronization among master device and slave devices in network, the accuracy ofgenerating the timestamps when send or receive the PTP messages directly influenced thesynchronization accuracy while using the protocol, which need hardware to assist to get thetimepackets in physical layer, we used the STM32F107VCT6produced bySTMicroelectronics as the assistant hardware, designed and build a hardware test platform forDCS’s time synchronization based on STM32F107VCT6,including the power module、serialport module、control module and Ethernet module,the all hardware boards were connected tocompose a synchronization network by Ethernet switch, analog a micro DCS, use theIEEE1588protocol to realize the accuracy time synchronization among all nodes.At last, this paper tested the time synchronization based on the hardware platform, the test was under different network situations(node to node and many nodes).The resultindicated that the time synchronization among the nodes can be accuracy about400nanoseconds, can meet the requirement of DCS’s time synchronization.