Implementations

Reliable industrial interface converter with TCP/IP extension

Purpose and assumptions

Industrial devices use various interfaces that are often incompatible with each other and are unable to communicate without additional equipment. To solve this problem, we have 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 allows the user to additionally control the data flow and redirect it to the Cloud using network interfaces. This technology is an essential part of building a modern 4.0 Industry 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 enabling communication with a computer network allows for a wide range of dynamic adaptation of the device to emerging needs and tasks. A wired Ethernet interface solution was used, connected to a socket in the popular RJ45 8-pin standard. Additionally, the system has been expanded by adding the possibility of wireless communication via Bluetooth and WiFi modules.

The basic operation of the device provides for two operating modes:

  • Direct connection
    We have designed software that allows easy control of communication by setting parameters on the server. The entire protocol configuration process takes place in a web browser – the user sets the transmission speed, number of data bits, stop bits, parity and CRC control.
  • COM port – hub
    The desktop application we have created for transparent support of virtual serial ports (COM) enables convenient integration of the device with existing tools using this type of communication. We ensure cross-platform compatibility with MS Windows, Linux and MacOS operating systems.

EMC compatibility, climate tests, safety

The possible importance of the device imposes the obligation to guarantee immunity to electromagnetic disturbances occurring in industrial environments and to meet emission requirements in accordance with the EU EMC directive. Numerous systems are used to decouple both low-frequency and high-speed interference. Added protection against overvoltage and electrostatic discharge on each input/output connection. The device is equipped with additional grounding connections to ensure the highest protection.

We performed climatic tests under the full load of the system in a temperature and humidity range exceeding the requirements of industrial standards. The experience of our engineers allowed us to achieve above-average results and ensure guaranteed reliability in all conditions.

Additionally, the highest security of devices connected to our converter was ensured. Thanks to the introduction of optical isolation of the input/output ports, in the event of a failure of one of the communicating devices, the remaining devices are not exposed to overvoltages not exceeding 3kV. Interfaces that remain in a state of suspended communication or those that have not been connected at all in a given configuration are subject to impedance matching using active terminal termination. This procedure improves the signal quality of other devices on a common bus and provides protection against electromagnetic wave reflection, which carries a potential risk of damaging the signal source.

Mechanics

Thanks to the small size of the device, durable insulating housing, solid screw connections, and practical DIN rail latches, a very convenient and refined mechanical solution has been achieved. Well-thought-out and ergonomic arrangement of input/output sockets allows for flexible connection configuration even in the most difficult-to-access places in the factory. Additionally, the system has been adapted to service work thanks to facilities based on a modular structure.

Front-end

We have designed and developed an intuitive and transparent front-end of the application, which makes using the converter even more enjoyable. We achieved excellent user experience using the following technologies:

  • Javascript
  • Vue.js
  • Bootstrap
  • Protocol Buffers
  • Python
  • Flask
  • C++
  • libserialport

Hardware

We decided to adapt two versions of the computing unit – Cortex-M4 STM32 or Xtensa ESP32. The choice of the microcontroller to be installed depends on the configuration of the interfaces used and the software dedicated to the product’s application. Physical support for RS232, RS485, USB, M-Bus, Ethernet, Wifi, and Bluetooth standards has been implemented. Such flexibility allows for a convenient selection of technology and optimization of production and operating costs. Operation in a wide range of power supply conditions has been refined, both with DC and AC voltage. Advanced optimization allows for low power consumption and the implementation of battery power.

Firmware

All device processes are controlled based on the FreeRTOS real-time operating system. Network connectivity was implemented by using an open LwIP stack, which means multiple devices can communicate regardless of their physical differences. Additionally, the stack is characterized by automatic connection stabilization in the event of energy or communication problems. Full functionality is restored without the need for user intervention. Support for various TCP/IP protocols has been implemented, including telnet, modbus-tcp, http and https. Modbus-RTU/ASCII was used for asynchronous serial transmission. Google’s Protobuf data sequencing method was also used.

Summary

When designing the converter, we wanted to create a system that would have the following features:

  • versatility – the ability to be used with various software and hardware;
  • dynamics and adaptability;
  • stability and safety.

The device we created met all the basic assumptions, and then some more. You can buy it from our client’s online shop!

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