Design Of PROFIBUS-DP Slave Station Based On CPLD

Fieldbus is more and more universal in the industry domain and PROFIBUS is oneof the most succeful, has gained the highest market share in various kinds of Fieldbusprotocol or standard. PROFIBUS is a kind of application type of system frame work andit could be divided into several subsets according to the different applications of variousconditions, in all its subsets, PROFIBUS-DP protocol is the most widely used inPROFIBUS specification currently. It is important to develop a universalPROFIBUS-DP communication port for simple industrial equipment or aPROFIBUS-DP intelligent slave station and connect port for most complex equipmentso that the equipment could exchange data with PROFIBUS and be controlled by themaster controller in PROFIBUS.A PROFIBUS protocol analysis chip named SPC3and a CPLD is used as the corein this design to implement a PROFIBUS intelligent slave station through the researchof PROFIBUS communication system structure, the processing of PROFIBUSintelligent slave station, the communication protocol of PROFIBUS and its transmissionmode. The slave station this paper designed could communicate to PROFIBUS masterstation with PROFIBUS to achieve the control of the output mode, control mode, outputvalue and monitoring the status of an industrial power supply. According to the statusthat the DP slave station located in, the modules in CPLD could be mainly divided intothe initialization module, the interrupt processing module and data exchange processingmodule, beyond all that, there is a driver module for CPLD to read or write SPC3andan address or data generator module. The operation of the whole slave station isachieved by three modules in CPLD which controlling SPC3’s status. The papersimulates and debugs the module that mentioned and designed above to ensure thecorrectness of the functional and timing of the modules after achieving all the modulesin CPLD.With experiments through experimental system that consist of PLC, aPROFIBUS-DP slave station with programmable touch screen, PC with RS-232/RS-485converter, the PROFIBUS-DP slave station this paper presented could be recognized byPROFIBUS correctly and communication with the other stations on PROFIBUS as anintelligent PROFIBUS slave station perfectly.