Toughness and flexibility make all the difference

USB cables for industrial digital image processing

In digital camera technology, the USB interface is proving to be one of the leading standard interfaces. Vital for the interference-free transmission of large data quantities, it must be able to withstand high mechanical loads whilst offering high EMC protection in any situation. For clean signal transmission, one camera manufacturer recommends its customers a USB cable suitable for industrial applications, which can now be used at lengths of up to 10 m.

“It’s so easy!” is the company philosophy at IDS Imaging Development Systems GmbH, Obersulm. “Our compact cameras are oriented towards the central customer advantages of simple installation and simple practical use,” explains Marketing Manager Thomas Schmidgall. “We always make sure of top quality, right from the initial development stage and this includes our accessories!”

For cameras used in tough industrial image processing situations, IDS offers its customers the specially developed USB cables from igus®, as its accessories of choice for high data transmission. The industrial-standard ‘Chainflex® CFBUS.065’ and ‘CFBUS.066’ are recommended for dynamic movements in measuring and testing engineering or for use in robots. “The sturdiness and signal quality convinced us right from the beginning,” recalls the Marketing Manager. “Above a length of 5 m we only specify the industrial-standard cables from igus® for perfect data transmission. Conventional cables cannot withstand the mechanical and electrical loads over time.”

Image processing for all requirements
IDS have been developing components for digital image processing since 1997. The products are used in industrial automation, quality assurance, medical, and security applications. With more than 60 employees and a global distribution network, IDS is an international player.

More than 90,000 “Frame Grabbers” and 30,000 “uEye” USB cameras sold around the world are figures that speak for themselves as far as the success of this still young company is concerned. “We have only been supplying cameras for image processing for the past three years. In 2003 we made the strategic decision of getting more into digital technology, and have been producing the respective camera models since 2004. In the meantime, they have taken over as our main business,” says Thomas Schmidgall.

Industrial-standard, compact, sturdy and innovative: These are the features of this camera family. This not only includes the Standard “uEye”, but also the “uEye RE” for rough environments. Both models have been designed for professional use and have an USB 2.0 interface available with an industrial, screw-type plug connection. “Thanks to the use of USB technology, well known and widespread in the field of consumer goods, our cameras can be connected to a wide range of different systems without any problems,” says Thomas Schmidgall. Camera control and power supply are via a USB interface.

USB in automation technology

Right from the word go IDS was sure Universal Serial Bus (USB) would be the system of the future. “When we ventured out in camera technology, we decided to rely on the USB standard which is spreading more and more in industrial applications, too,” explains Thomas Schmidgall.  “Today, every computer, every PDA has a USB interface. And more and more suppliers of control technology are tending towards standard devices and thus standard interfaces. The USB interface is gaining more and more ground even in industrial PCs. It is small, allowing the devices connected to be kept correspondingly compact,” says the Marketing Manager.

Camera technology is the showcase field in industrial USB technology. It is usually used in a moving environment, for example on a robot gripper, requiring a sturdy, stable connection for data transmission that is suitable for energy chains and as waterproof as possible. “The problem of length limitation was the main obstacle here,” remembers Thomas Schmidgall.

 “We spent a lot of time looking for possibilities of achieving a transmission length of 10 m for industrial applications, so that no further interference-prone components have to be used. Before we came across the Chainflex® cables, we tested numerous cables from a wide range of other suppliers. None of them met the requirements of interference-free signal transmission.” The USB connection as such is not the problem, rather the systems failed again and again due to mechanical and electrical loads on the cables.

The search for a suitable cable
A meeting with igus® took place at the Vision trade fair in Stuttgart, in 2005. The company presented a Fire Wire cable for travel distances of up to 10 m for industrial applications – with a transmission rate of up to 400 Mbit/s for moving applications.

“That was the start of our cooperation,” remembers Rainer Rössel, responsible for everything related to Chainflex® cables at igus®. “The inspiration for supplying an industrial-standard USB cable came from IDS. On account of the fact that USB is making its mark as the standard interface in the IT-world, this technology is becoming more and more important in automation technology. However, it makes especially high mechanical and electrical demands on the cable. We accepted this challenge and now supply two USB cables for highly dynamic applications.”

Whereas the ‘CFBUS.065’ shows its strength for signal transmission up to 5 m, the ‘CFBUS.066’ is used for applications up to 10 m. In the first case, the wire cross-sections of the bus elements are reduced to a minimum. This results in an overall outer diameter that is small enough for a standard USB plug. If distances of greater than 5 m are required, the cross-sections of the bus elements have to be enlarged due to the damping behaviour and the differences in signal run time, and the shield design has to be changed – with the disadvantage that the overall diameter of the cable increases and thus no longer fits in a standard USB plug. “In such cases, we remedy the situation with the IDS M8 plug,” says Rainer Rössel.

“We worked hand in hand right from the word go. IDS provided us with a camera so that we could test the cables in our own testing laboratory. And the trial is still running. So far, at least 4 million movements have taken place with the camera, and the image quality has not deteriorated one little bit,” says Rainer Rössel.

Both USB cables cover a broader standard in visualised automation technology. They can be used for bend radii of only 75 mm with speeds of up to 10 m/s. Tests have shown that there is no increase in damping even at high cycle figures of more than 4 million strokes.

The bus pair and power supply cores in the USB cables are stranded with a short pitch length. The bend-resistant braided copper shield has approx. 70 % linear and 90 % optical cover, and achieves high damping stability even at high cycle figures. The TPE outer sheath, extruded under high pressure, extremely abrasion-resistant, oil-resistant and flame-resistant, provides the necessary cable protection to avoid wires breaking. The cables have UL/CSA approval and are DESINA-conform.

Industrial suitability is reflected in the materials used and their manufacture, which guarantee the high resistance levels of the cables. They stand out in particularly hot or cold, particularly dirty or oily environments. Their range of possible uses is correspondingly large, ranging from tooling machines and aircraft construction, from clean room or deep-freeze applications to semiconductor placement.

Good advice is of the essence
 “We were approached by IDS about a sturdy cable technology for industrial applications, and developed the USB cables on the basis of the specifications provided,” says Rainer Rössel. “We always see ourselves as a problem solver for our customers’, which is why the right advice at the beginning of the project is extremely important.  This is the stage where firm requirements have to be clarified. These include mechanical loads, environmental or application conditions. A cable is often underestimated, but without it the planned application will not work.”

During visualisation use, the requirements on the transmission of data are especially high. “The signal quality of the USB cables used is very good. We carried out a large number of comparative tests in advance; the igus® cables were the right solution at the end of a long search; their quality had us convinced,” concludes Thomas Schmidgall.

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