A probe contact system is capable of adjusting distances between tips of the contactors and contact targets with simple and low cost mechanism. Further, the method includes detecting an abnormal traffic; and updating the table entry with packet information of the MODBUS request message. The system includes multiple controlled light sources and the horizontal and vertical line cameras are configured to track eye motion in response to light stimulus provided by the light sources according to a programmed algorithm. A cost-effective control strategy of said switches based on an energy prediction of said coding error is also proposed. The carriages and the rail and floor system are modular, enabling the components of the system to be shipped knocked-down and assembled on site, and to be expanded or contracted after installation. The data retriever determining means determines a data retriever in accordance with the extracted information.