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When designing an electronic system, cables are oftentimes the last component specified in by engineers. However, when the ideal cable system is expected to last the life of the equipment, it is important to develop a system of cables that are reliable in terms of their durability and ability to maintain proper signal integrity.
Unplanned downtime is unacceptable, in any industry or application. Therefore, cable systems represent the “lifeline” of modern machinery. In today’s heavily automated technology, moving applications pose many challenges to design engineers, who have to decide what form of a cable is the best fit—round or flat. Presented here are a few criteria to consider when making that choice.
Depending on the market and application of intended use, round and flat cables each excel in particular settings. Round cables have long been the industry standard, and are used in most industrial applications from automated and general types of manufacturing to renewable energy.
Flat cables, while currently a niche solution, can offer a great solution for supplying power and data to machines within the medical, semiconductor, and civil-aircraft markets, among others. Flat or festoon cables are also highly sought after in the overhead crane market for companies that do not want to wind cables around spools.
Electromagnetic interference (EMI): This includes both internal and external sources. Internal EMI protection varies and depends heavily on the cable’s construction. Standard (unpaired) flat cables do not perform well as data cables. If designers run individual shielded pairs in a flat cable, it will provide crosstalk and coupling protection pair to pair.
It is very difficult to place an overall shield on a flat cable, as the shielding material tends to become round—it will not hold a flat format. This makes external EMI protection of flat cables very difficult and not readily available, because this natural shielding tendency provides better protection against external EMI for round cables.
Crosstalk: This is the uncontrolled coupling of signals between two transmission circuits. Similar to EMI protection, using varied pair lay lengths within either a flat or round cable enhances protection against crosstalk.
Attenuation: This ultimately determines the maximum length of a signal cable and conductor resistance, which impacts voltage drop on a power component. In most cases, attenuation tends to be worse when using a flat cable. Higher-quality insulation is used and proper placement of the ground can improve attenuation, resulting in flat construction. Some very-high-performance (low crosstalk and attenuated) flat cables are produced for certain industries.
One of the reasons power and signals are able to combine into a single cable is due to shielding. For example, the HELUKABEL TOPSERV Hybrid’s shielding protects it from EMI.
The four main types of mechanical stress placed on cables are rolling flex, torsion, tic-toc, and S-bend. Round cables can withstand all of them due to their natural ability to move in multiple axes at once. In certain applications, round cables are able to withstand 30 million flexing cycles before they need to be replaced. Flat cables are best suited for rolling flex, because this movement is in one linear axis.
Rigorous testing ensures cables won’t fail in torsion applications.
Movements that require multiple axes such as torsion can cause the flat cable to bind or only twist to a certain point. Under torsional loads, the cable gets twisted and spooled over a certain length. Thus, every component must be integrated at the right twist and position, and be wrapped or embedded with a PTFE-tape (Teflon), to minimize the friction forces during torsion.
Table 1 summarizes the types of motion and the preferred cable type for each.
Cables are exposed to many environmental stressors that can cause cable to degrade over time if the proper materials are not used during the cable’s manufacturing. Some of these stressors include UV, oil, radiation, abrasion, high or low temperature, and friction. Knowing these factors in advance will strongly influence the selection of material properties (polyimide/foamed polyethylene, etc.) for conductor isolation and cable jacket materials (polyurethane).
Some flat cables may be pocketed. To evenly distribute loads and generally be more robust, it is more beneficial if the flat cable is extruded as a single piece.
Most PVCs or PTFEs used in round cables can be created to withstand many of these environmental stressors while maintaining their flexibility. Flat cables that are extruded with silicone will be able to withstand high temperatures. However, silicone is a softer material and doesn’t provide much abrasion and friction resistance, which could expose the inner conductors to potential failures.
Cable Design and Production
Round cables are designed to maximize space within the smallest cross-sectional area required. This allows round cables to fit in most panel or machine openings that otherwise might be a problem for a flat cable with an elongated cross-section—i.e., square peg, round hole.
Space is important, and circles work well for processing, i.e., drilling a hole is normally easier than cutting a rectangle. However, flat cables may be able to be stacked to fit together with less space than round cables.
Furthermore, flat cables need to be weighed and balanced precisely to make sure movement is uniform. This is only required for round cables when they are installed in a cable track. Round cables only require fillers and tapes to ensure concentricity.
The weight and softness of a cable’s design is to optimize ergonomic performance for the end user, especially when the application is a handheld device (Table 2).
Finally, special tooling is required to encapsulate all flat-cable components into a single cable. Cable-manufacturing equipment is standardized to produce round cables, so the additional tooling turns into an extra manufacturing cost for customers.
Advanced applications in today’s industrialized society require cables to manage not just one type of stress at a time, but often multiple types. Some examples include:
Abrasion and cut resistance: Because the cable system is spooled on reels and pulled over concrete and sharp edges, the outer jacket material needs the right shore-hardness for these parameters (polyurethanes have a good track record).
Low elongation at high tensile load: This is achieved by a double-wall extrusion process, in combination with an aramid-braid (Kevlar/Vectran) in between to take mechanical stress off of the inner components. This construction type minimizes the tensile load placed on the inner conductors, which reduces fatigue and early cable failure.
Using a strength member in cable constructions reduces the reliance on the copper, thereby reducing the total amount of copper used and ultimately cutting down on cable size, weight, and cost. Such types of constructions might not be possible with flat cables that rely on silicones and PTFEs to encase multiple conductor components.
Jacketing is a serious application consideration. This round sewer cable in a pipeline robot must resist abrasion, UV, oil hydrolysis, and even microbial attacks.
In summary, many options are available when it comes time to design a cable system. Engineers should use a design funnel or checklist to narrow down the options in order to develop the solution that best meets an application’s electrical and mechanical requirements. Using this approach will ensure the cable design—round or flat—is optimal and gives all parties confidence that the cable system is durable and reliable.From machinedesign Friday, June 2, 2017
GE’s rugged, Linux-ready COM Express Type 6 Basic module integrates AMD’s dual- or quad-core R-Series SoCs at up to 3.6GHz, and offers -40 to 85°C support.
GE Intelligent Platforms’s bCOM6-L1700 is the first Linux-friendly computer-on-module we’ve seen to run AMD’s latest “Bald Eagle” R-Series system-on-chips. You get a choice of dual- or quad-core models on the module, which adopts the 125 x 95mm COM Express Type 6 Basic form factor.
(click image to enlarge)
The bCOM6-L1700 is designed for challenging harsh environments that are subject to extremes of temperature, vibration, and shock, says GE. The module is especially useful for those applications in which “maximum uptime is mission-critical such as heavy industry, transportation, military/aerospace, and energy exploration,” says the company.
The module supports -40 to 85°C operating temperatures, although these figures are said to be CPU dependent, suggesting perhaps that only the dual-core model is up to the task. The COM supports up to 16GB of soldered ECC DDR3 RAM for extra robustness, but there are no claimed specs for shock and vibration resistance.
In addition to the 16GB of RAM, there’s an optional onboard SATA SSD ranging up to 64GB, as well as a gigabit Ethernet controller. Interfaces expressed via the COM Express connectors include four SATA 3.0 connections, and a choice of SD or GPIO interfaces.
bCOM6-L1700 core chipset block diagram
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Multimedia interfaces include DisplayPort, eDP, VGA and HD Audio I/O. Additional I/O includes four USB 3.0 ports and eight USB 2.0 ports, although the block diagram suggests there might be 10 USB 2.0 interfaces. For expansion, you get seven PCIe 2.0 x1 lanes and a PEG interface.AMD R-series APU architecture
(click image to enlarge)
A CEC05 carrier board is available for the module, although GE had no details on it. The company also offers custom carrier board development services.
Specifications listed for the bCOM6-L1700 include:
AMD Embedded R-Series with AMD Radeon HD GPU:
RE427BDGH44JA (4x x86 Steamroller cores @ 2.7GHz to 3.6GHz); 8x GPU cores @ 600MHz to 686MHz; 4MB L2 cache; 35W TDP
RE225FECH23JA (2x x86 Steamroller cores @ 2.2GHz to 3.0GHz); 3x GPU cores @ 464MHz to 533MHz; 2MB L2 cache; 17W TDP
Memory — up to 16GB soldered DDR3 with ECC
Optional onboard SATA SSD up to 64GB
4x SATA 3.0 6Gbps interfaces
SD interface (or setup selectable swap for 8x GPIO)Display:
eDP (embedded DisplayPort)
VGANetworking — Gigabit Ethernet controller
4x USB 3.0
8x USB 2.0
SPI, LPC, IRExpansion:
7x PCIe 2.0 x1 lanes or various combinations
PEG (PCIe Graphics) or swap for 2x “8 Gen 3”
8x GPIO (or setup selectable swap for SD interface)Ruggedization:
-40 to 85°C operating temperature (CPU dependent)
Pre-mounted heat sink/spreader
Alarm sensors for temperature
Shock/vibration — “Increased shock and vibration immunity; depends on carrier/system design”
Optional conformal coatingDimensions — 125 x 95mm (4.79 x 3.74 in.); COM Express Type 6 Basic
Operating system — Linux; Windows 7/XP; VxWorks
“The [bCOM6-L1700] modular design, based on open standards, is ideally suited for next generation Industrial PCs, and will provide a path for automation controller system solution providers to scale in design based on AMD technology in those demanding environments,” stated Sameer Gupta, Marketing Manager, Industrial Controls and Automation, AMD Embedded Solutions.
No pricing or availability information was provided for the bCOM6-L1700 module. More details may be found on the GE Intelligent Platforms bCOM6-L1700 product page.
From linuxgizmos Monday, March 9, 2015
The RLX-IH Wireless Communication device creates an alternative to running costly cable, particularly where connectivity is not feasible, is prohibitively expensive or physically impossible. Operating at 2.4GHZ, RLX-IH radios feature high speed at long ranges and low latency, at 1-2 msec. They are well-suited for PDA/laptop connectivity, and support high-speed applications such as Voice/IP, video over Ethernet or security cameras. Other features include less maintenance than slip rings; data collectors for wireless sensors; 11 Mbps data rate for fixed devices; connectivity to any 802.11-compliant access point; and redundant master radios and self-healing features for dependability.From automationworld Thursday, March 2, 2006
Inscentinel, a UK-based biotechnology company, has developed a handheld sensor integrated with live bees to detect dangerous substances in the air. The VASOR136 (volatile analysis by specific olfactory recognition) portable device is designed to hold 36 bees in six cassettes within the device.
Trained bees held within the device
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Bees have a keen sense of smell and researchers at Inscentinel have trained the honeybees to detect odours associated with a variety of explosive mixtures and compounds, such as Semtex, PE4, DMNB, gunpowder, C4, TNT and hydrogen peroxide. When the bees detect a particular odour, they produce a proboscis extension reflex response (PER) and stick out their tongues expecting food. Bees have the capacity to detect trace vapours in parts per trillion levels. They are easily available and can be trained within a short time period.
The bee holders in the VASOR136 contain microcontrollers, photo sensors and heat resistors. They are clipped into six-bee cassettes and the bee holders are made to face an infrared light-emitting diode. A PER event interrupts the infrared beam and the readings are communicated to the VASOR devices’ display.
Inscentinel researchers have also demonstrated that honeybees could be trained to diagnose diseases such as tuberculosis.From azosensors Friday, April 1, 2011
The new DT Series 3-Wire Current Transducer from NK Technologies is specifically designed in a compact, space-saving case. The DT 3-Wire uses a common point for both power supply and output signal, and is factory calibrated for a single current range. This 3-wire method for DC current measurement keeps costs in check for projects where many sensors are needed.
“Reliability is key in all monitoring applications, and there are gains in reliability whenever the number of connection points can be reduced,” explains Philip Gregory, President, NK Technologies. “With the addition of this new series of sensors, NK Technologies has provided the system designer even more choices to measure DC current.”
The DT 3-Wire features industry standard outputs of 0-5 or 0-10 VDC proportional to the DC current. It is powered by 24 VDC, factory calibrated, and compact and easy to install. It’s commonly used in applications like photovoltaic panel monitoring, hoists, DC motor protection and wind driven generators. The DT Series complements NK Technologies’ existing DLT Series of 4-–20 mA current output sensors. When specified controllers can read only voltage output sensors, the DT 3-Wire provides the same space saving properties without the need to add an external dropping resistor, consequently removing another place where trouble could occur.
>>For more information on this product, click hereFrom automationworld Sunday, December 15, 2013