[Vídeo do projeto]

Team: Grupo 05:
João Álvares (Coord.) , Tomás Neves , Carlos Teixeira , Francisco Bastos
Company: FFONSECA
Supervisors: Osvaldo Pacheco (DETI)
Miguel Valente (The Company)
Sérgio Gonçalves (The Company)

Accurate temperature monitoring is essential in numerous industrial processes, and the PT100 probe is a trusted reference in this field. With this in mind, FFONSECA challenged us to develop an innovative solution that enables temperature readings via a PT100 probe and the transmission of this data using the IO-Link protocol. This system not only ensures high reliability and precision in data collection but also facilitates integration and communication with other industrial solutions, promoting efficiency and modernization of processes.

This should be the full project description. Do not repeat what is in the summary above. Accurate temperature monitoring plays a vital role in countless industrial processes, where precision and reliability are critical for maintaining quality, safety, and efficiency. The PT100 probe, recognized for its stability and precision, stands as a trusted benchmark in this domain. Leveraging the robust capabilities of the PT100, FFONSECA presented us with the challenge of developing a cutting-edge solution that combines accurate temperature measurement with seamless industrial communication. Our solution is an innovative system designed to read temperature values through a PT100 probe and transmit the collected data via the IO-Link protocol. By merging precision sensing with advanced digital communication, this system ensures reliable, accurate data collection and integration into modern industrial environments, fostering enhanced efficiency and process modernization.

Key Features of the System

  1. Precision Temperature Measurement At the core of the system lies the PT100 probe, which offers highly accurate resistance-based temperature readings. These readings are processed through a carefully designed signal conditioning circuit that ensures noise-free, linearized data for precise measurement.

  2. Robust Data Processing The STM32F4 microcontroller is responsible for processing the signal from the PT100, converting it into digital values, and performing key calculations. Using the PT100’s standard formula, the system determines real-time temperature values and calculates parameters such as resistance and maximum and minimum recorded temperatures.

  3. Advanced Communication through IO-Link The integration of the MAX14827 transceiver enables the system to transmit data using the IO-Link protocol, a modern standard for industrial communication. This ensures compatibility with a wide range of industrial networks and facilitates seamless data exchange with control systems.

  4. Configurability and Versatility The system allows customization to suit different applications, including support for PT100, PT500, and PT1000 sensors, as well as configurations for 2-wire or 3-wire connections. Additional settings, such as offset calibration and sampling options, provide further flexibility.

  5. Comprehensive Data Transmission The system transmits essential temperature data (current, maximum, and minimum values) with high resolution (0.1°C) and also provides resistance values (0.1Ω resolution). Beyond real-time data, asynchronous requests enable the transmission of product-specific information, such as the manufacturer’s name, serial number, production date, and device name.

  6. Compact and Industrial-Grade Design The solution features a compact PCB design, built to fit within robust industrial enclosures and equipped with an M12 connector for seamless integration with existing setups.

Challenge

A temperature probe of the PT100 type (thermoresistance) generates a resistance signal that typically cannot be interpreted by control systems, such as PLCs. While many PLCs are capable of interpreting these signals, the cost factor often makes this solution less viable for common applications. The aim is to develop a PT100 probe signal converter to IO-Link communication, which is increasingly popular in the industry, to be integrated into industrial temperature measurement sensors. Temperature is one of the most frequently measured quantities in the industry, and there is growing demand for communication solutions to obtain measured data, as well as parameters from the sensors themselves, such as operating time, internal temperature, maximum internal temperature, etc. The goal is to create a converter with a standard M12 connector capable of being integrated into temperature probes manufactured by the company.

Proposed Solution

The project “IO-Link Converter for Temperature Probes” aims to develop a device that converts the analog signal from a PT100 probe into digital communication using the IO-Link protocol. This device is designed to facilitate the integration of industrial sensors into modern monitoring and control systems, enhancing efficiency and reliability in industrial processes. To achieve the desired outcome for the company, several essential tasks need to be completed, including the development of the PT100 reading circuit, implementation of the IO-Link protocol, creation of a compact PCB, and testing and validation of the results. The project development involves several key stages: Hardware Development: Designing a circuit that accurately reads the PT100 probe signal and converts it into a format compatible with digital systems. Firmware Development: Implementing the IO-Link protocol to ensure efficient and robust communication between the sensor and control systems. Compact Design: Creating an integrated and optimized design to accommodate all components, including the connection via an M12 connector, widely used in the industry.

This approach ensures that the final product is reliable, compact, and ready for use in demanding industrial applications, contributing to the modernization of temperature monitoring and control systems.

Block diagram of the Project

Architeture

Project Hardware

The project aims to achieve precise temperature measurements using PT100 probes. The system is powered by a 24V source and uses the MAX14827 transceiver to supply 3.3V to the circuits. A constant current of 5mA flows through the PT100, whose resistance varies with temperature, generating a proportional voltage that is adjusted by an ADA4096-2 operational amplifier before being read by the STM32F4 microcontroller. The microcontroller converts the voltage into digital values and calculates the resistance and temperature using the standard PT100 formula. The data is transmitted via UART to the MAX14827 transceiver, which adapts them to the IO-Link protocol for integration with industrial networks. The system sends data such as current, maximum, and minimum temperature, as well as resistance, in addition to product information (manufacturer, serial number, production date, and name). Initial configurations include sensor type (PT100/PT500/PT1000), number of wires, offset, and average samples. Temperature values (14 bits) and resistance values (13 bits) are transmitted with resolutions of 0.1°C and 0.1Ω, respectively. Product data can be requested asynchronously.

Results

This project has delivered significant advantages, including enhanced temperature measurement precision, robust data accuracy, and seamless integration with industrial networks via the IO-Link protocol. These advancements streamline the workflow for industries relying on high-accuracy temperature readings, such as process control and automation, by reducing manual interventions, ensuring consistent measurement reliability, and enabling real-time monitoring of critical parameters. Throughout the project, the team gained valuable technical expertise in developing and implementing current-driven temperature sensing systems, conditioning signals with precision amplifiers, and programming microcontrollers like the STM32F4 for efficient data processing and transmission. Additionally, the integration of the MAX14827 transceiver to achieve IO-Link compatibility expanded our knowledge of industrial communication protocols, ensuring scalability and adaptability for a wide range of applications.

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