本热水供水循环系统的控制采用西门子S7-200 PLC系统、一台监控上位机（或触摸屏）和配套上位控制软件实现现场各种参数的监控。-Control of the hot water circulation system using Siemens S7-200 PLC system, a monitoring host computer (or touch screen) and supporting higher-level control software implementation of