How single-board computers extend the reach of industrial automation
universal asynchronous receivers/transmitters (UARTs), dual micro HDMI ports that support 4K output, and more. Industrial Shields’ Raspberry Pi Ethernet PLCs use the BCM2711B0, operate with 12 VDC to 24 VDC input voltages, and draw up to
topologies like ad-hoc, master- slave, and client-server. The original program has an intuitive application programming interface (API) for Arduino environments. Industrial Shields recently adapted SimpleComm for the Linux environment found on Raspberry Pi PLCs.
available to run on most Arduino and Raspberry Pi PLCs. Industrial automation networks need high-speed and deterministic communication. PROFINET focuses on deterministic performance that delivers messages exactly when needed and expected. That means delivering each message with the appropriate speed based on the task being performed. Not all tasks are equally time sensitive. PROFINET can deliver messages on various protocols, including: ■ PROFINET Real-Time (RT) ■ PROFINET Isochronous Real- Time (IRT) ■ Time Sensitive Networking (TSN) ■ TCP/IP (or UDP/IP) Conclusion A wide range of SBC-based PLCs and industrial networking devices based on Arduino and Raspberry Pi technologies are available. They use open-source software and, in some cases, open-source hardware. Arduino PLCs are available as standard-sized units for small networks, micro PLCs for space-sensitive installations, and machine controllers for embedded applications. Quad-core Raspberry Pi-based PLCs can support more complex industrial networking applications. Raspberry Pi-based IPCs and IIoT gateways that support high levels of flexibility in network design and deployment are available.
Figure 5: Examples of RevPi Core SE IPC (left) and RevPi Connect IIoT Gateway (right). Image source: KUNBUS
Figure 3: The Portenta Machine Control board is designed for embedded applications in a wide range of machines. Image source: Arduino
supervisory control and data acquisition (SCADA) software for controlling, monitoring, and analyzing industrial devices and processes. The availability of full root access speeds up the implementation of custom programs. The RevPi Core S and SE are built on an open hardware and open software platform that conforms to the IEC 61131 standard. RevPi Core S units are compatible with all KUNBUS expansion modules, including fieldbus gateways. RevPi Core SE units are compatible with KUNBUS I/O modules but don’t support the fieldbus gateways. RevPi Core S/SE IPCs have USB, Micro-USB, Ethernet, and HDMI connections. They feature a 1.5 GHz quad-core processor with 1 GB RAM, and models are available with 8, 16, and 32 GB of storage. For example, model PR100360, RevPi Core S has 16 GB of memory. To support IIoT connectivity, the RevPi Connect S and SE Gateways are available with up to 32 GB of memory and include two RJ45 10/100 Ethernet sockets, two USB ports, a 4-pin RS-485 interface, plus micro-HDMI, and micro-USB
sockets. The two Ethernet sockets support simultaneous connectivity with automation and information technology (IT) networks. As an open-source software platform, applications can be programmed using Node-RED, Python, and C. RevPi Connect can be upgraded with PROFINET, EtherNet/IP, EtherCAT, Modbus TCP, and Modbus RTU functionality without the use of expansion modules. Examples of RevPi Connect units include: ■ PR100363, RevPi Connect S with 16 GB memory ■ PR100197, RevPi digital I/O expansion module ■ PR100250, RevPi analog expansion module PROFINET and SBC PLCs SBC PLCs can be sophisticated devices capable of supporting advanced networking protocols. Process field network (PROFINET) is an open standard for industrial networking devices like PLCs, drives, robots, diagnostic tools, etc. It runs over industrial Ethernet and is optimized for collecting data and controlling industrial equipment with real-time communications. It’s
IPC and IIoT gateway solution
It can connect to various external sensors and actuators with isolated and programmable digital and analog I/O connections, three configuration temperature channels, and an I2C connector. Resettable fuses protect all I/Os. Network connectivity is supported by USB, Ethernet, Wi-Fi, BLE and RS-485. Raspberry Pi for factory automation More complex automation tasks can benefit from the processing power of Raspberry Pi 4-based PLCs using the Broadcom BCM2711B0 processor. Fabricated on a 28 nanometer (nm) process, the BCM2711B0 uses the Cortex-A72 architecture. It has four cores with a clock speed of 1.5 GHz and 4 GB RAM. It integrates numerous peripherals, including timers, interrupt controller, general purpose I/O (GPIO), USB, PCM/ I2S digital audio interface, direct memory access (DMA) controller, I2C masters, serial peripheral interface (SPI) masters, PWM,
1.5 A of current. They include the Linux operating system and have dual Ethernet ports, dual RS-485 ports, Wi-Fi, BLE, and CAN bus options, making them capable of connecting with many devices using multiple protocols and communications ports. They have been optimized for applications that benefit from real-time control and are available with 2, 4, and 8 GB of RAM. Examples of Industrial Shields’ Raspberry Pi PLCs include: ■ 012003000200, with 4 GB RAM and 21 I/Os a (Figure 4) ■ 012003001100, with 4 GB RAM and 54 I/Os ■ 016003000200, with 4 GB RAM,
When greater flexibility is needed, designers can turn to KUNBUS’ RevPi Core S and SE IPCs and the RevPi Connect S and SE IIoT gateway, all based on Raspberry Pi and designed for DIN rail mounting (Figure 5). In addition to providing circuit diagrams, KUNBUS uses an open-source adaptation of the Raspberry Pi operating system (OS) with a real-time operation patch. The Raspberry Pi OS offers robust interoperability with a wide range of software applications developed for Raspberry Pi. KUNBUS works with software vendors to support
21 I/Os, and general packet radio service (GPRS) cellular connectivity
Bridging Arduino and Raspberry Pi in PLCs with SimpleComm The SimpleComm C++ library lets designers send data using RS-485, RS-482, Ethernet, and other protocols. It can be adapted to different communications
Figure 4: Industrial Shields’ Raspberry Pi Ethernet PLC with 4 GB RAM and 21 I/Os. Image source: Industrial Shields
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