Tag Archives: SG-Tronic

An open-source PLC to control the Internet of Things


Controllino is the first software open-source, Arduino-compatible PLC. 


Designed by the SG-Tronic team, the Controllino is an open-source programmable logic controller (PLC) built around Atmel’s ATmega328 and ATmega2560 microcontrollers (MCUs). Recently funded on Kickstarter, the Arduino-compatible PLC allows Makers to produce and control their next Internet of Things project, ranging from industrial to home automation applications.

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“When I was at electronic school, I would have loved Arduino. But back then, microcontroller programming wasn’t that easy. When I became aware of Arduino, I thought… What a great idea for young people and those who are not hardcore microcontroller programmers,” creator Marco Riedesser explained. “The only problem with Arduino is [that] when you don’t really know so much about electronic hardware, driving more than a LED can become difficult. And using an Arduino board in a professional project or even a product that you want to sell is quasi impossible if you want to get certification.”

Now fully UL and CE-certified, Makers can begin creating and actually shipping gadgets such as drones, home appliances, or any other electronic project that comes to mind. The Atmel powered PLC is currently being presented in three models: Mini, Maxi and Mega.

“I had to repair the coffee machine for my brother-in-law. I thought it would be easy to use Arduino but there was nothing on the market that could handle switching high voltage and high current. So I thought I had to come forward with a product,” Riedesser revealed to TechCrunch earlier this year.

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All Controllino PLCs are equipped with an internal RTC using SPI, which can be switched on/off and allow for the use of SPI for other purposes via pin header. With built-in processor contact, Makers have a direct link to a number of boards (like Arduino). All pins are also 4000V ESD protected. What’s more, both the Controllino Maxi and Mega let users select between internal RTC and Ethernet using SPI, as well as turn it off so they can use the SPI for other purposes via pin header.

The versatile device works in altitudes up to 2,000m above sea level, in temperatures ranging between 5°C to 55°C, and in maximum relative humidity 80% for temperatures up to 31°C decreasing linearly to 50% relative humidity at 55°C. Each Controllino features an automatic input voltage range selection. This internal function changes voltage dividers ratio on the processor input, and enables the use of one input for analog and digital and for 12V or 24V input voltage range without user action. In addition, the Controllino’s main supply voltage fluctuates up to ±10% of the nominal voltage

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Key Mini specs:

  • MCU: ATmega328 MCU
  • RTC
  • Clock speed: 16 MHz
  • 1x RS232 interface
  • 1x SPI interface
  • 6x relay outputs (230V/6A)
  • 8x digital outputs (2A @12V or 24V)
  • 8x analog/digital inputs
  • 10A input current max

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Key Maxi specs:

  • MCU: ATmega2560
  • RTC
  • Clock speed: 16 MHz
  • Ethernet connection
  • 2x RS232 interface
  • 1x RS485 interface
  • 1x I2C interface
  • 1x SPI interface
  • 10x relay outputs (230V/6A)
  • 12x digital outputs ( 2A @12V or 24V)
  • 12x analog/digital inputs
  • 20A input current max

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Key Mega specs:

  • MCU: ATmega2560 MCU
  • RTC
  • Clock speed: 16 MHz
  • Ethernet connection
  • 2x RS232 interface
  • 1x RS485 interface
  • 1x I2C interface
  • 1x SPI interface
  • 16x relay outputs (230V/6A)
  • 24x analog/digital inputs
  • 12x digital outputs – high side switch (2A @12V or 24V)
  • 12x digital outputs – half-bridge (2A @12V or 24V)
  • 20A input current max

Interested in learning more? You can check out Controllino’s official page here. Those wishing to purchase the Mini, Maxi and Mega can now do so for € 119.00, € 199.00 and € 269.00, respectively.