Design and Implementation of an Electric Control System for Slit-Scanning and Calibration Instruments of the YNAO NVST

The NVST (New Vacuum Solar Telescope) of the Yunnan Observatories (YNAO) is for observations of fine solar structures though high-resolution imaging instruments and spectrometers in conjuncture with polarization analyzers.During observation with the NVST the slit scanning and motions of the polarization measurement instruments need to be controlled synchronously with the data-collecting systems.In this paper, we present the design and implementation of an electric control system to remotely control motions of these instruments (including the polarization analyzers and slit-scanning devices) according to observational requirements.The remote control is achieved using a server computer from which commands are sent to control machineries associated with various separate controllers via a serial port on the computer and then a LAN network.Needed data and messages are fed back to the client through the LAN.The system is designed based on WinSock network programming and serial-port communication programming using the TCP and UDP protocols.The control system incorporates a software system for operation in the Server/Client architecture.Our experimental results show that this control system is effective in controlling the instruments on the NVST, and the design incorporating network/serial-port communications provides excellent extensibility for subsequent upgrading of the NVST to expand its functions.