Creating IoT-based products for manufacturing facilities, remote locations, or Edge Computing environments is much more than simply developing an effective electronic circuit and software stack. When creating products for these types of harsh applications, there are many factors that engineers need to consider; from mechanical stress and extreme temperatures, to electromagnetic interference, and the required data transmission rates that far exceed what most consumer products can provide. Engineering Internet-of-Things High-Stress Industrial Environments.
Designing the Product’s Physical Structure
The scope of what is involved in creating the physical environment in which a product exists goes far beyond merely making it look nice as Industrial Designers also define the size, shape of the outer enclosure, routing of cabling through it, and locations of mounting points and seal locations. Therefore, the designer works with Mechanical Engineers at an early stage of the project to determine thermal paths, ways to manage cable-strain-relief and spaces that have been reserved for placing gasketing materials so that a specific Ingress Protection rating can be achieved. Material selection does not stop once selections have been completed since it influences how the product performs in all different types of environments. For example, aluminum die-cast products dissipate heat well and act as shields for electrical signals while polyamide filled with glass allows for maintaining the structural integrity of the case while minimizing the overall weight; stainless steel fasteners provide corrosion-resistance when exposed to chemical/coastal environments.
At this point in time, selection of a connector type limits the available connection types. Selection of a connector type such as an M12 x coded connector at this point in time allows for the correct panel hole cut-out, PCB footprint and cable diameter allowance. However, retrofitting an industrial connector into a case designed for a standard RJ45 connector usually results in mechanical changes being needed and/or delays to obtain certification testing.
Environmental Standards
Failure due to vibration, dust and moisture accounts for the vast majority of all failure modes in industrial electronics. Teams determine the worst possible environmental conditions prior to starting their schematic design.
IP (Ingress Protection) ratings relate physical requirements to quantifiable values. An IP65 rating prevents dust entry and low pressure water jetting. An IP67 rating permits temporary submersion up to 1 meter. An IP69K rating covers high pressure and high temperature wash-down processes typical of food/beverage processors. All of these ratings require corresponding physical designs for enclosures, cable glands and connectors that match each other’s classes. A single component with a lower rating reduces the entire assemblies rating.
High Speed Ethernet in Rugged Applications
Many modern industrial applications are transmitting large amounts of machine vision data, sensor arrays or synchronized control signals requiring Gigabit or Multi-Gigabit Ethernet. To maintain signal integrity over mechanical stress and near sources of electromagnetic interference (such as variable frequency drives), the physical layer must function properly.
M12 connectors have become a de facto interface for industrial Ethernet but selecting the proper coding scheme is important. D-Coded versions use four contacts and support 100 Mb/s data transfer speed which still meets current requirements for legacy Fieldbus Systems and smaller sensor networks. Engineers choose the coding scheme based upon expected data volume, cable length and shielded requirement needs. If multiple coding schemes exist at the same facility, clearly identifying them to avoid incorrect mating during commissioning is essential.
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