How single-board computers extend the reach of industrial automation Written by Jeff Shepard
Figure 1: The model IS.MDUINO.21+ from Industrial Shields has 13 inputs and 8 outputs. Image source: Industrial Shields
Embedded PLC for small machines Designers of small machines for labelling, forming, and sealing, carton packing, gluing, electric ovens, industrial washers and dryers, mixers, and so on can turn to the 170 x 90 x 50 millimeters (mm) Portenta machine control PLC. It has a DIN bar compatible housing and push-in terminals for fast connection and is rated for operation from -40°C to +85°C without external cooling (Figure 3). The main processor is the dual-core STM32H747 with a 480 MHz Cortex M7 and a 240 MHz Cortex M4. The board can support flat screen displays, touch panels, keyboards, joysticks, and mice for installer and operator interfaces. It can be programmed using the Arduino PLC IDE or other embedded development platforms. The Portenta Machine Control can support predictive maintenance and artificial intelligence (AI) software. Its embedded RTC supports synchronization of processes and enables real-time data collection and remote control of equipment.
maintenance algorithms. Secure over-the-air (OTA) firmware updates are supported by the onboard secure element and X.509 compliance. Opta PLCs are available in three variants differentiated by their communications capabilities. All three include USB-C. The models are: ■ Opta Lite, model AFX00003, that adds 10/100BASE-T Ethernet ■ Opta RS485, model AFX00001, that adds 10/100BASE-T Ethernet and half-duplex RS-485 ■ Opta Wi-Fi, model AFX00002, that adds 10/100BASE-T Ethernet, half-duplex RS-485 802.11 b/g/n Wi-Fi, and Bluetooth low energy (BLE) These micro PLCs have eight programmable analog/digital inputs and four normally-open relay outputs rated for 10 A (2.3 kW). The real-time clock (RTC) has a typical ten days of power retention at +25°C, and network time protocol (NTP) synchronization is available through the Ethernet port. They are DIN rail compatible to speed system integration (Figure 2).
The availability of single-board- computers (SBCs) like Arduino and Raspberry Pi, rated for use in industrial environments together with software development tools based on the International Electrotechnical Commission (IEC) 61131-3 standard, have opened new opportunities for machine and factory automation designers. Some of these new SBC-based solutions also open new possibilities for automating environmental monitoring, smart home and building installations, agricultural applications, and other non-industrial systems. Industrial SBCs are being used in machine controllers, industrial PCs (IPCs), Industrial Internet of Things (IIoT) gateways, micro programmable logic controllers (PLCs), soft PLCs, analog and digital input/output (I/O) modules, and more. These SBC-based devices are built on open hardware and open software platforms, sometimes including full root rights. Compliance with IEC 61131-3 means that the five standard automation programming languages are supported, including ladder diagram, structured text,
function block diagram, sequential function diagram, and instruction list. Being built using SBCs means developers can also turn to languages like Java, Python, C, or C++, providing greater flexibility than traditional industrial control hardware. Some support data security from the hardware to the Cloud or a higher-level network like an enterprise resource planning (ERP) system with an onboard secure element and International Telecommunications Union (ITU) X.509 Standard public key compliance. This article presents examples of SBC-based solutions available to machine and automation designers from Arduino, Industrial Shields, and KUNBUS for various applications, including small- to medium-scale automation, embedded control in small machines, and large factory automation installations. The article closes with a look at how PROFINET and deterministic networking can be implemented on SBC PLCs.
Arduino-based PLCs is the availability of the Arduino PLC integrated development environment (IDE) for writing
■ 2 Interrupts (5 VDC to 24 VDC)
■ 6 software configurable as analog (0 VDC to 10 VDC, 10 bit) or digital (5 VDC to 24 VDC) ■ 8 Outputs: ■ 5 opto isolated digital (5 VDC to 24 VDC) ■ 3 software configurable as analog (0 VDC to 10 VDC, 8 bit), digital (5 VDC to 24 VDC), or pulse width modulated (5 VDC to 24 VDC) ■ 256 KB memory ■ Ethernet, RS-232, RS-485 and USB communications ■ Expandable with up to 127 modules
control software. The Arduino PLC IDE enables users to choose any of the five programming languages defined by IEC 61131-3 and quickly code PLC applications or port existing ones. It also includes ready-to-use Arduino sketches (programs), tutorials, and libraries. Industrial Shields’ Arduino-based PLCs can be programmed using the Arduino IDE or directly using C. These PLCs include open-source tools and can be programmed with multiple software platforms. They can be programmed through the USB or Ethernet ports for remote connections. Users can continuously monitor the status of all the variables, inputs, and outputs. The model IS.MDUINO.21+ from Industrial Shields is rated for operation from 0°C to +60°C, and its ATmega processor achieves a throughput of 16 MIPS at 16 MHz (Figure 1). Features include: ■ 13 Inputs: ■ 7 opto isolated digital (5 VDC to 24 VDC)
Micro PLCs The Arduino Opta is a micro PLC designed to support IIoT
applications. Programmable with the Arduino PLC IDE, it supports Arduino sketches and standard PLC languages. The main processor is the dual-core STM32H747 with a 480 MHz Cortex M7, a 240 MHz Cortex M4, and 1 MB program memory that supports real-time control, monitoring, and implementation of predictive
Figure 2: Opta Lite Arduino micro PLC showing the four 10 A relay outputs on the left front of the unit. Image source: Arduino
Arduino PLCs
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