IO-Link smart industrial sensors reference design

21st November 2013
Nat Bowers

Thanks to close cooperation with TMG Technologie und Engineering and Maxim Integrated, Renesas has announced a new reference design for small scale IO-Link smart industrial sensors. The hardware platform of the new IO-Link solution comprises Renesas' RL78 16-bit ultra-low power microcontroller, and an IO-Link transceiver and a miniature sensor from Maxim. The software and applications are completed with TMG TE's IO-Link v1.1 device stack operating on the microcontroller.

Using conventional 3-wire sensor cables to transmit serial digital communications between sensors/actuators and industrial automation systems, the IO-Link protocol is an open standard according to IEC61131-9. IO-Link provides visibility down to field device level, automatic parameterisation and central data management, process, parameter and diagnosis data transmission over one bi-directional medium, remote configuration and commissioning, backward compatibility to current sensor switching technology.

Enabling IO-Link technology to enhance sensor networking in an increasingly smart and automated world, Renesas' new solution introduces the new RL78 MCU family to IO-Link applications and addresses the challenges met by designers wanting to bring smart and intelligent features to miniature sensors.

Requiring no more than 6 mm x 25 mm of PCB space, the solution described in the reference design enables driect interfacing with the board via an industry standard M12 connector and cable. Unconstrained by its small size, the board offers the key benefits of a development platform. This includes a debug interface allowing users to flash/debug the on-board microcontroller with ease, and develop their applications. The board is packaged with full software evaluation setup and a programming/debugging adapter doubling as an extended prototyping area, which offers users access to a high accuracy 12-bit A/D converter and multiple serial communications.

The MAX14821 transceiver from Maxim acts as the physical layer interface to the microcontroller running the data-link layer protocol. It supports all the specified IO-Link v1.1 data rates. In addition to the IO-Link channel (Pin-4 of the M12 connector), additional 24V digital inputs and outputs are provided (Pin-2 of the M12 connector). The on-board C/Q and DO drivers are independently configurable for push-pull, high-side, or low-side operation. The device detects the IO-Link C/Q wake-up condition and generates a wake-up interrupt signal to the microcontroller. The C/Q input and digital inputs have selectable current loads for use in actuators. The C/Q output and the digital output have a 100mA drive capability.

Supplied in a 25-pin 3 mm x 3 mm package, the small scale IO-Link smart industrial sensor reference design includes a RL78/G1A microcontroller. Offering ultra-low power consumption ranked among the best in the industry, the RL78/G1A MCU offers multiple new features including reduced current consumption down to 66uA/MHz, 64KB on-chip programmable flash memory with 1.8V operating voltage, high accuracy 12-bit A/D converters, and 32MHz high speed on-chip oscillator with +/- 1% accuracy over the temperature and voltage range. Along with numerous advanced safety features and an on-chip temperature sensor, the RL78/G1A also features 4KB on-chip data flash with background operation for IO-Link sensor data storage, 16-bit multi-function timers, and multiple serial communication channels for interfacing with sensor components. Two DMA channels ensure high speed data transfer between peripherals without affecting the CPU load.

The on-board MAX44008 miniature sensor from Maxim integrates six sensors: red, green, blue sensors; an ambient light sensor; a temperature sensor; and an ambient infrared sensor with an I2C interface. Offering the user a variety of options for sensor application development, the device has a wide and dynamic range of light measurement, providing robust and precise information for ambient colour sensing and colour-temperature measurement.

The IO-Link device stack supports the IO-Link functionality according specification V1.1. It is based on a modular software design with a strict separation of protocol stack, application and hardware abstraction. The stack provides the highest performance and efficiency, whereby the sensor data is already prepared before the reception of the master command. It also ensures the consistent process data exchange. The stack is provided free of charge for evaluation purposes, along with a sensor demo and accompanying IO-Link description file.

The release of this new kit is planned for Q1/2014.

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