The Development Of The PROFIBUS-DP Slave Station

Fieldbus is the trend of the automation technology development . PROFIBUS has already become one of the openly international standards and been used widely in the whole world, which provides the new market opportunity.It is convenient to use ASIC (Application for Special Interface Chip) as the interface of slaves. The software pattern for slaves is more advanced . The author must understand the details of the protocol. The following is finished :1. The slave station is achieved with the ASIC SPC3 (Siemens Profibus Controller No 3) . In this stage, the main job includes: PROFIBUS-DP (Process Field Bus for Decentralized Peripheries) system configuration, the state mechanism, and the analysis of frame structure. The PROFIBUS-DP system is already in operation. This pattern is generally used, and its cost is expensive because of the kit.2. The protocol of PROFIBUS-DP communication among masters and slaves is studied, especially about the message frame structure and bus timing. It is the foundation of programming the FDL (field data-link layer) protocol through software. The C51 and assemble language are adopted. The advantages of the two languages are performed.By the program which achieves the function of the FDL ,the slave station may communicate with the master station in no more than 500kbps. The MCU (Microcontroller Unit) with our software can replace the special protocol chip and achieves the function from SAP56 to SAP62(service access point).