The system hardware is composed of upper and lower computer.
系统硬件由上位机和下位机两部分组成。
And software system of upper and lower computer was introduced.
并介绍了其上、下位机的软件系统。
This system consists of upper and lower computer component. the lower computer uses S7-200 PLC to collect field data of the gas-gate station;
系统采用上下位机协作模式，以S7-200 PLC作为下位机处理核心，负责采集门站现场数据；
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