The purpose of implementation and its main goals
Industrial devices use different interfaces, which are often incompatible with each other and are not able to communicate without additional equipment. To solve this problem, we designed a converter whose main function is to enable data exchange between production line controllers, robots, HMI screens, and servers. Basing the project on a microcontroller also allows you to control the flow of data and redirect them to the cloud using network interfaces. This technology is an essential part of building a modern industry 4.0 system.
Many uses
We have created a universal system ready to perform various functions depending on the software and hardware version.
The use of a fast interface allowing communication with a computer network allows a wide range of dynamic adaptation of the device to emerging needs and tasks. A wired Ethernet interface solution based on the popular 8-pin RJ45 standard was used. In addition, the system was expanded by adding the possibility of wireless communication via Bluetooth and WiFi.
The basic device abilities provide two modes of operation:
- A direct connection
We have designed software that allows easy control of communication by setting parameters on the server. The whole protocol configuration process takes place in a web browser – the user sets the transmission speed, the number of data bits, stop bits, parity, and CRC control. - COM port – hub
We have created a desktop application for transparent support of virtual serial ports (COM) that allows convenient integration of the device with existing tools that use this type of communication. We have ensured cross-platform compatibility with operating systems such as MS Windows, Linux, and MacOS.
EMC compatibility, climate tests, security
The responsible function of the device imposes an obligation to guarantee immunity to electromagnetic disturbances occurring in industrial environments and to meet the emission requirements in accordance with the EU EMC Directive. Numerous decoupling systems were used, both low-frequency and fast signals. We have added overvoltage and electrostatic discharge protection at each input/output connection. The device has been equipped with additional grounding connectors for the highest protection.
We performed climate tests under full system load in the temperature and humidity range exceeding the requirements of industrial standards. The experience of our engineers has allowed us to achieve above-average results and ensure guaranteed reliability in all conditions.
In addition, the highest security of devices connected to our converter was taken care of. Due to the introduction of optical isolation of the input/output ports in case of failure of one of the instruments communicating with each other, the others are not exposed to overvoltages that exceed 3 kV. Interfaces that remain in a suspended state of communication or those that have not been connected in a given configuration are subject to impedance matching using active termination of terminals. This treatment improves the signal quality of the rest of the devices on a common bus and is a protection against the reflection of the electromagnetic wave that carries the potential threat of damage to the signal source.
Mechanics
Thanks to the small size of the device, durable insulating casing, solid screw connections and practical DIN rail snaps, a very comfortable and refined mechanical solution has been achieved. Thoughtful and ergonomic distribution of input/output sockets allows flexible configuration of connections even in the most difficult places available in the plant. In addition, the system has been adapted to service work thanks to facilities based on a modular design.
Front-end
We have designed and made an intuitive and transparent front-end application that makes the operation of the converter even more pleasant. We have achieved excellent user experience using the following technologies:
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Hardware
We decided on the adaptation of two versions of the computing unit – Cortex-M4 STM32 or Xtensa ESP32. The choice of the mounted microcontroller depends on the configuration of the interfaces used and the dedicated software for the application of the product. Physical support for RS232, RS485, USB, M-Bus, Ethernet, Wifi, and Bluetooth standards has been implemented. Such flexibility allows a convenient selection of technology and enables the optimization of production and operating costs. We also refined operation in a wide range of power supply conditions, both with DC and AC voltage. Advanced optimization allows low power consumption and the implementation of battery power.
Firmware
All device processes are controlled by the FreeRTOS real-time operating system. Connectivity via the network was implemented by using the LwIP open stack, which means that many devices can communicate regardless of their physical differences. In addition, the stack is characterized by automatic connection stabilization in the event of energy or communication problems. Full functionality restoration occurs without the need for user intervention. Implemented support for various TCP/IP protocols, including telnet, Modbus-TCP, HTTP, and https. Modbus-RTU/ASCII was used for asynchronous serial transmission and Google’s Protobuf was used as a data serialization method.
Summary
When designing the converter, we wanted to create a device that would have the following features:
- versatility – can be used with various software and hardware;
- dynamics and adaptability;
- stability and security.
The device we created met all the basic requirements and the first series is already in production.
