Transmissor de Temperatura Multicanal com Comunicação RS485 – MODBUS

Abstract

The use of measuring equipment in industrial processes makes the process more accurate and safe. In recent years these devices have advanced technologically notably, mainly with the advent of microprocessors and microcontrollers and the evolution of electronic components in general. The sensors scan the information from the shop floor and send it to other devices through industrial network protocols. The industrial networking protocols commonly found in the industry are MODBUS, PROFIBUS, AS-I, DEVICENET, CANopen, INTERBUS, LONWORKS, BACnet. This work aimed to create a multichannel temperature transmitter with RS485 – MODBUS communication that besides providing the values of the read temperatures allows the user to easily set up monitoring temperatures allowing to turn on or turn off others equipments when necessary, easy installation and still save on wiring at the time of installation. The use of temperature as a measurement variable was justified because it is one of the variables most used in the process control industry. As temperature sensing element were used the thermocouples and for converting the electromotive force signal from the thermocouples to °C was used the IC MCP9600. The implementation of the MODBUS communication protocol was performed with an 18F4550 microcontroller and for the RS485 electrical interface was adopted the IC MAX13451. A standard Windows program has also been coded and through this program all parameters of the transmitter can be configured and monitored by an operator. Finally, the transmitter and configuration set proved to be easy to configure, parameterize and install.