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A Step Toward Standardized Sensor Connectivity

Written by Jeff Child

I’ve been following the work the PICMG consortium since its inception back in 1994. The “P” in PICMG standards for PCI, but certainly the group has evolved way beyond the old parallel PCI bus, just as our computers have. Over the years, PICMG has been clever about adapting each relevant computing technology from the PC and server market and outfitting them for the embedded board-level computing realm. And its branched even beyond the computing world into the IoT space.

 Along just those lines, over the past five years PICMG has been working on specifications aimed at industrial IoT (IIoT). The idea is to link an IIoT network architecture and an edge device form factor to PICMG’s embedded computing standards like COM Express and others. As part of this effort, Micro Sensor Adapter Module (MicroSAM) was the first of these PICMG standards to reach ratification back in October 2020. MicroSAM is an open specification that defines a 32mm × 32mm module hardware platform for traditional sensor vendors wishing to quickly create smart sensors. MicroSAM enables a fundamentally different IIoT architecture, offering a distributed architecture with true Plug and Play network integration.

 Clearly MicroSAM satisfies a need never before addressed by other industry specifications: a compact module targeted at microcontrollers for each of the Industrial IoT sensor nodes. The processing performance and I/O connectivity are targeted toward the sensor interface. MicroSAM may exist in parallel with other embedded technologies. MicroSAM devices provide sensor connectivity, while PICMG standards such as COM Express, CompactPCI Serial or MicroTCA provide higher layers of control.

 In early October (this year), the PICMG consortium announced the ratification of IoT.1 specification defining a communication standard between sensors / effecters and local IoT controllers such as MicroSAM already specified by PICMGs IoT.0 specification. The IoT.1 specification defines a firmware interface and low-level data model that provides for vendor-independent configuration of smart sensors and effecters, as well as plug and play interoperability with higher levels of the installation. IIoT.1 supports both sensing and profiled motion control required by most emerging Industry 4.0 applications.

 According to PICMG, the IoT.1 specification is the first work product from consortium based on collaboration with the DMTF organization. PICMG’s IoT.1 specification leverages and extends the Platform Level Data Model (PLDM) specification from Distributed Management Task Force (DMTF) in order to address the needs of industrial automation and control. PLDM is a low-level messaging system that supports topologies, eventing and discovery and runs over a variety of system level buses such as I2C/SMBus and PCIeVDM (Vendor-Defined Message) over MCTP (Management Component Transport Protocol) as well as RBT (RMII-Based Transport (RMII = Reduced Media Independent Interface)) over NC-SI (Network Controller Sideband Interface).

 There are four specific ways that the IoT.1 benefits the industry, according to PICMG. First, it enables sensor vendors to create smart sensors without having to manufacture the control circuitry and/or software by purchasing these components from PICMG-compliant suppliers. Second, it allows controller suppliers who wish to create smart sensors or smart-sensor components to do so in a way that is interoperable with other suppliers. Third, the spec lets sensor/effecter integrators to integrate sensors/effecters from multiple vendors with controllers from multiple vendors. And, fourth, IoT.1 is expected to accelerate the uptake of smart-sensor technology through open-specifications and interoperability.

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 When combined with the PICMG sensor-domain network architecture and data model, sensors connected to MicroSAMs (PICMG IoT.0) or other controller modules will seamlessly integrate into the network with plugand- play interoperability, according to the group. The IoT.1 was developed in collaboration with the PICMG members Arroyo Technology, nVent, Triple Ring Technologies and Sandy Systems. More information is available at www.picmg.org.

 I look forward to following this exciting new spec as embedded computing vendors and their customers adopt it in their industrial IoT implementations.

PUBLISHED IN CIRCUIT CELLAR MAGAZINE• NOVEMBER 2021 #376 – Get a PDF of the issue

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Editor-in-Chief at Circuit Cellar | Website | + posts

Jeff Child has more than 28 years of experience in the technology magazine business—including editing and writing technical content, and engaging in all aspects of magazine leadership and production. He joined the Circuit Cellar after serving as Editor-in-Chief of COTS Journal for over 10 years. Over his career Jeff held senior editorial positions at several of leading electronic engineering publications, including EE Times and Electronic Design and RTC Magazine. Before entering the world of technology journalism, Jeff worked as a design engineer in the data acquisition market.

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A Step Toward Standardized Sensor Connectivity

by Jeff Child time to read: 3 min