Trends in industrial automation

The vertical integration of management execution systems with factory floor equipment has led to the convergence of the Ethernet TCP/IP protocol with industrial field buses. Several Ethernet variations for industrial have emerged, including Profinet, Ethernet/IP, ModbusTCP/IP, EtherCat, and Ethernet Powerlink. Each protocol addresses very specific needs.

Most industrial Ethernet automated systems do not require a faster cycle times than a few milliseconds. For these applications, the industrial Ethernet protocol can be cost-effectively implemented in software on any MCU with a Ethernet MAC peripheral. Due to their moderate flash size requirement, protocols like Modbus TCP can be implemented in a MCU.

Of course, many, many MCU makers offer Ethernet ports on their devices. Atmel offers ARM-based and 32-bit AVR microcontrollers with up to 512 Kbytes of flash and a 10/100 Ethernet MAC unit and a Media Access Controller (EMAC) peripheral with chained buffer DMA. The EMAC DMA acts as a master on the internal multilayer bus with multiple internal SRAM blocks enabling a true parallel data transfer between the Ethernet frames and the application data.

Reguarding MCUs for industrial apps, I spoke with Jacko Wilbrink, senior director of MPUs at Atmel. He said, “At a regular pace, over the past years, the number and complexity of processors and networked devices in industrial automation systems have grown. This raises concerns around overall power consumption and network security. Our customers are demanding MPUs with a combination of low power and security functions over a broad performance range. We are continuing to bring more MPUs to the market with just the right price-to-performance for our customers specific requirements.”

Atmel SAM9 MPUs are price-competitive solutions for implementing industrial Ethernet protocols, such as the Ethernet/IP standard, which requires a higher flash size and faster execution time. The SAM9G45 has a 400 Mhz ARM926EJ core with 32 Kbyte instruction and data caches and deterministic execution time using the TCM (tightly coupled memory) interface that enables access to the internal SRAM with zero wait states.

Renesas has available the R-IN32M3 multi-protocol communication LSI featuring fast real-time response and low power consumption. They target industrial communications with a two port Ethernet PHY. The IC has a real-time OS accelerator, a Cortex-M3 core, 1.26 Mbytes of RAM, and a serial flash interface.

It does not have an Ethernet controller, but Texas Instruments recently introduced the TMS320F28376D Delfino 32-bit MCU, which targets industrial apps with four independent 16-bit A/D converters, 40 PWM channels, six capture modules, three encoder inputs, and two CAN ports. No Ethernet here, but the chip can perform vibrational analysis and execute trigonometric controls loop algorithms because each of its dual 200-MHz C28x cores has a floating-point unit, a Viterbi-complex math unit, a trigonometric math unit, and a control-loop floating-point accelerator (CLA) unit. That combination with 512 or 1,024 Kbytes of flash with 166 or 204 Kbytes of RAM can handle high-performance control systems.