Research And Development On The VxWorks-based Communications Management Module For PLC

Local Control Unit (LCU) was an important component in Hydropower Plant Monitoring and Controlling System. Communicating with governor, exciter, relay devices via Communications Management Module was an effective solution in a Special-PLC based LCU device.Developing this device/module was a part of the LCU-upgrading-project from Hydro Division of Wiscom System. Firstly, the functions of Communications Management Module in LCU were defined, then functional requirements analysis was completed, and embedded system platform was choose under the functional requirements. Secondly, VxWorks was selected as the operating system on this module after comparative analysis of the current mainstream Embedded System Solutions. Thirdly, hardware platform was created according to the module's application needs and interface requirements, then VxWorks was ported to this hardware platform, and then the application software development environment was established. Fourthly, the structural analysis was used for application software analysis. According to the software's system analysis, the application software was developed in the module's software development environment, especially, the design of a circular queue structure used in system debugging agent sub-module was described here. Finally, the development trend of Communications Management Module was discussed, and this module may exist in a form of IEC 61850 Gateway before IEC 61850 became universal standard in power system.A detailed study on embedded system software design was included in this paper, which would be helpful on the other embedded system software development.