“Industrial facilities have become an increasingly complex network of cables, including the interconnection of Internet of Things (IoT) nodes in addition to digital Electronic interconnection devices. While digital networks have been standardized using wired protocols such as Ethernet and BACnet and wireless network protocols such as Wi-Fi and Bluetooth, control computers such as single board computers (SBCs) or programmable logic controllers (PLCs) and sensors or actuators However, the digital interconnection devices between peripherals and other peripherals vary widely.
Author: Bill Giovino
Industrial facilities have become an increasingly complex network of cables, including the interconnection of Internet of Things (IoT) nodes in addition to digital electronic interconnection devices. While digital networks have been standardized using wired protocols such as Ethernet and BACnet and wireless network protocols such as Wi-Fi and Bluetooth, control computers such as single board computers (SBCs) or programmable logic controllers (PLCs) and sensors or actuators However, the digital interconnection devices between peripherals and other peripherals vary widely.
To add to the confusion, interconnect devices use a variety of cables, connectors, and pinouts that look very similar but are completely incompatible.
It is the responsibility of the system designer to reduce these incompatibilities and ensure interoperability, while also reducing cost, speeding system assembly, and increasing reliability; even under harsh industrial environmental conditions. One way to do this is to standardize on IP67 or IP68 rated USB-C cable assemblies. This improves cable assembly compatibility across devices, which makes it easier for technicians.
This article describes digital interconnect device issues in industrial applications and how many of them can be addressed by standardizing USB-C cables and connectors for simple digital interconnect devices. This article then describes the various USB-C connectors and cable assemblies from PEI-Genesis, Amphenol LTW and Bulgin and their unique features, including IP67 compliance. It concludes with a discussion of how they provide ubiquitous reliable and robust connectivity for computer-to-sensor/actuator applications.
Digital Interconnect Devices in Industrial Automation
Industrial equipment is managed by a control computer, which can be an SBC, PLC, or a nearby laptop. Control computers are often connected to nearby devices required by industrial equipment, which can be broadly referred to as sensors, including switches, optical and environmental sensors, in addition to actuators such as motors, solenoids, or lights. For most heavy-duty industrial equipment, the equipment manufacturer’s designer selects the type of connector used for the cable end and selects the electrical protocol used. For custom industrial controls, engineers and technicians select and install computers, actuators, sensors, connectors and cables. Once the connector type and electrical protocol are selected, these cannot be changed later because the re-fitting process would be lengthy and expensive. Therefore, when planning industrial operations, the type of digital interconnect devices used by sensors and actuators must be decided very early in the design process. As with any system that makes extensive use of interconnected digital systems, the larger the scale of operation, the more time and money you can save by standardizing equipment, including cables.
Technicians must have the appropriate cables and compatible connector terminations readily available when setting up or reconfiguring equipment. At first glance, two electrically incompatible cable assemblies may appear to be identical, and may even have similar connectors that appear to mate, when in reality they are not. This non-obvious compatibility issue creates frustration for technicians and delays system deployment. Even with a proper cable, it may take several attempts to properly position the non-reversible keyed connector on the cable to the device to ensure a secure connection. Standardizing on one cable assembly can reduce frustration while ensuring interoperability between machines in low-light environments or where speed of deployment is critical. This not only saves time, but also costs, as cable assemblies can be purchased in bulk.
The Benefits of Digital Connectivity with USB-C
Suitable for most applications between industrial devices, USB-C cable assemblies solve the ubiquitous digital interconnection problem. USB-C plugs and receptacles are rotationally symmetrical, keyless, double-sided blade connectors that ensure a secure connection the first time you plug in, saving time and frustration, and technicians no longer needing to fiddle around to properly position a keyed connector . USB-C cables have the added advantage of providing power to sensors or actuators.
Industrial facilities can standardize on USB-C cables and connectors for most digital interconnects between control computers and sensors and actuators, simplifying cable assembly inventory management and connector interoperability. Industrial IP67 USB-C cables and connectors are heavy-duty products that can withstand the high temperatures, solvents, and liquids commonly found in harsh industrial facility environments. USB-C industrial cables also minimize power and signal loss, and are more resistant to undue bending and twisting forces.
The USB-C connector supports USB 2.0 and USB 3.1. The USB-C standard requires USB 3.1 ports and cable assemblies to be backward compatible with USB 2.0 480 Mb/s speeds. This allows USB 2.0 ports to use the same cable assemblies as USB 3.1, preventing compatibility issues. However, USB 3.1 supports much higher speeds. USB 3.1 Gen 1 Cable Assemblies support speeds up to 5 Gb/s and USB Gen 2 Cable Assemblies support speeds up to 10 Gb/s. To identify transfer speeds, the USB specification requires that cable assemblies with USB-C connectors on both ends have an electronic marker chip embedded in the connector housing to identify the maximum power and data transfer speed of the cable assembly. The data in the electronic tag chip is read by the USB host when it is first plugged in and tells the USB host the maximum transfer speed of the cable to ensure that the USB host sends data correctly. USB-C cable assemblies that only support USB 2.0 speeds do not require an electronically marked chip, so if no chip data is sent, the USB host will send data at 480 Mb/s.
The maximum power delivery allowed by the USB-C standard is 5 V DC and 3 A, for a total power of 15 W. This is the standard for common USB cable assemblies. However, the USB 3.1 Gen 1 and later specifications allow 100 W at 20 V and 5 A. USB-C cable assemblies designed for USB 3.1 power delivery must contain an electronic marker chip that identifies the power delivery capacity, otherwise the USB host will default it to 15 W. This prevents damage to the cable due to power overload, improving safety.
While the focus here is on USB-C cable assembly standardization for digital interconnect devices, it is important to know that there are three cable assembly capacities:
USB 2.0 Mode: Unmarked, provides 15 W of power and 480 Mb/s of data
USB 3.1 Gen 1: Electronically marked with 100 W of power and 5 Gb/s of data
USB 3.1 Gen 2: Electronic marking, providing 100 W of power and 10 Gb/s of data
If a lower capacity USB-C cable is used with a properly configured higher capacity USB-C host and device, the USB host will limit power and data to the lower capacity. This prevents power overload on the cable for improved safety, while ensuring data rate compatibility for improved reliability. Industrial facilities can further simplify operations by using only the standard that provides the maximum required power and data transfer. Standardizing on USB 3.1 Gen 1 cable assemblies is a safe bet unless industrial automation facilities perform high-speed data operations, such as streaming live video. Typically, 5 Gb/s USB 3.1 Gen 1 specifies a maximum cable length of 2 m, which is sufficient to allow the control computer to connect to nearby sensors and actuators. If 10 Gb/s data needs to be sent reliably, USB 3.1 Gen 2 specifies a cable length of 1 m. When sending 10 Gb/s data over a longer cable, data on the cable may be lost due to signal reflections or attenuation.
USB-C cable assembly
For designers who want to send high-speed data in harsh environments, there are many robust and reliable solutions to choose from. For example, PEI-Genesis offers the IPUSB-31WPCPC-1M Sure Seal IP67 USB 3.1 Gen 2 Cable Assembly (Figure 1). The cable is 1 meter long and is rated to operate from -20°C to +85°C, making it suitable for most harsh industrial environments. The cable jacket is made of polyvinyl chloride (PVC) resin with good water resistance and ultraviolet (UV) resistance. Commercial jackets can crack or discolor with prolonged exposure to sunlight.
Figure 1: The Sure Seal IPUSB-31WPCPC-1M is a 1 m long USB-C cable assembly made for industrial applications. Connectors come with locknut gaskets for a secure IP67 watertight connection to sensors or actuators. Dimensions shown are in millimeters. (Image credit: PEI-Genesis)
The IPUSB-31WPCPC-1M is molded from PVC resin at one end and has a standard USB-C plug connector and a stainless steel USB-C plug. This end connects to the USB host connector on the SBC or PLC. The other end has a sealed molded plug with a nylon lock nut and rubber gasket. This provides a strong and secure IP67 seal for connections to sensors or actuators.
The Sure Seal IPUSB-31WPCPC-1M contains an embedded electronic marker chip to indicate its capacity to the connected device. Electronic marker chips operate over the full temperature range of -20°C to +85°C for cable assemblies. This ensures that the cable is properly identified even when the device is opened at any extreme temperature.
USB-C connectivity in extreme environments
For extremely harsh environments, Amphenol LTW offers the 1 m USB-C cable assembly UC30FL-NCML-SC01 (Figure 2). The entire cable is covered with polypropylene plastic (PP) conduit for additional protection from shock, cutting forces and bending strain at corners. The conduit also provides protection for the cables enclosed within it under extreme vibration conditions. The conduit is glued to both ends of the cable and cannot be removed.
Figure 2: The UC30FL-NCML-SC01 USB-C cable assembly is wrapped in a PP conduit to protect it from shock and severe vibration. Dimensions are in millimeters. (Image credit: Amphenol LTW)
The cable assembly has a common USB-C host connector on one end that plugs into a USB host. The other end has a heavy-duty circular connector; this connector has enhanced pull resistance and has a sealed molded plug and silicone gasket secured with a nylon lock nut to provide water resistance and good air tightness, Resistant to most chemicals. The cable and circular connector are IP67 rated to protect the circular USB-C plug from the environment with or without mating, even when unconnected.
The fire performance of UC30FL-NCML-SC01 reaches UL94V-0, that is, the PP cable can withstand 10 seconds of flame. PP cables are also resistant to oil, gasoline and most solvents. Each plug is capable of operating from -40°C to +85°C, the nylon lock nut and PP conduit can withstand higher temperatures, from -40°C to +115°C. Therefore, this cable assembly is particularly suitable for connecting sensors and actuators of industrial gasoline engines and generators.
An embedded electronic marker chip indicates that the cable supports 5 Gb/s data transfer and is suitable for high-speed gasoline generators that require constant monitoring of engine operation to maximize efficiency.
USB Sensors in Marine Applications
In some cases, the device’s control computer has a USB-A port, but needs to be connected to a USB-C port. A cable such as Bulgin’s PXP4040/C/A/2M00 USB-A to USB-C Cable Assembly (Figure 3) is required. This cable has a USB-A plug on one end and a round USB-C plug on the other end and operates between -40°C to +80°C. After two weeks of immersion in 10 m deep water, the USB-C connector and cable were still functional. It is also resistant to salt water and is suitable for marine equipment, including industrial machinery on tankers and freighters. Cable assemblies are rated IP68, except for the USB-A connector, which is rated IP66.
Figure 3: One end of the PXP4040/C/A/2M00 is a USB-A plug and the other end is a USB-C plug. It is salt water resistant, and the USB-C plug can still function normally after two weeks of immersion in 10 m deep water. (Image credit: Bulgin)
Bulgin’s PXP4040/C/A/2M00 flameproof grade reaches UL94V-0. The cable jacket is made of PVC resin and is suitable for offshore deck applications.
The USB-C cable housing is made from polycarbonate-polybutylene terephthalate (PC/PBT), a high-strength material commonly used in car bumpers. PC/PBT connector housings are highly chemical resistant and flexible enough to withstand high shocks down to -40°C. Even with a strong impact, the connector will not shatter, only slightly cracked. This provides the USB security sensor with resistance to vandalism, including anti-freeze attacks, where the connector is quickly frozen and then hit with a hammer.
The USB-C specification does not allow electronic marker chips to be embedded in cables with a USB-A plug on one end. The cable assembly is rated to deliver up to 5 A and supports data rates up to 5 Gb/s over a 2 m length, but some USB-C peripherals may find no electronic marking chip and default to 480 Mb/s transfer rate.
Standardizing USB-C cable assemblies for digital interconnects in industrial environments simplifies cable inventory management and makes connections quick and easy thanks to the rotationally symmetrical design of the plug and receptacle. A USB-C cable can indicate its power and data transfer capabilities to the host computer to prevent data loss and dangerous power overload conditions. Proper selection and use of the appropriate USB-C cable assemblies in industrial systems can also improve reliability, reduce maintenance, and reduce overall costs.