基于RS-485通信的温度水位远程测控系统

　　为满足太阳能热水工程远距离测控的需要，设计了一个基于单片机控制的温度和水位远程测控系统。系统的主机和从机均以ATmega16为控制器，二者通过RS-485通信，距离可以超过1 km。用NTC热敏电阻作测温元件，使用单片机内置的10位A/D转换模块实现多路温度的测量。通过非对称式多谐振荡器电路把水位转换为振荡频率，再用计数器测量频率来实现水位的测量。给出了主机和从机的完整电路及功能，较详细地介绍了水位和温度的测量电路以及传感器参数。

　　Abstract:

　　To satisfy the demand of long-distance control of solar hot water project， a remote measurement and control system of temperature and water level was introduced. ATmega16 was applied as controller in both master and slaver which communicated by RS-485. The communication distance can exceed 1km. With NTC thermistor as temperature sensor， multi-channel water temperature was measured by a 10 bit A/D convertor embedded in ATmega16. An unsymmetrical oscillator was utilized to convert the water level to oscillating frequency which was measured by a counter. In this paper， the circuit diagrams and function of master and salver were given， the measurement circuit of water level and temperature and sensors parameters were also introduced in detail.