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Pepperl+Fuchs Blog

Why the Incredible G10 Housing is an AS-Interface Game Changer

Posted by Helge Hornis on Tue, Mar 11, 2014

AS-Interface is all about simplifying the designs of a control system, reducing the complexity of the wiring,cutting the cost of the installation, improving diagnostics, and making automation more productive.

For over 20 years, the 350 AS-Interface hardware suppliers have always tried to push the technology a bit further. Pneumatic specialists have designed powerful AS-Interface controlled pneumatic valve blocks, companies with expertise in motor control are offering motor starters that connect directly to AS-Interface, and experts in the field of indicators and user input devices are offering stack lights, acknowledgment buttons, and even numerical displays.

G10 Module is a Game Changer for AS-InterfaceClearly these are excellent solutions. But these devices address specific needs and are thus a relatively small subset of what most AS-Interface users require daily. I/O modules designed to bring sensor data to the PLC and allow actuators to be controlled are far more typical.

G10, a housing so compact you probably wouldn’t recognize it as an I/O module!

All installations using the AS-Interface flat cable have one thing in common: The need to build up the actual network; and here I am talking about routing the cable, bridging between several network subsegments, as well as making it easy to connect I/O devices to the network.  It is easy to overlook the "plumbing" of AS-Interface, but paying a bit more attention here is not just a good idea, it can result in significant simplification, cost reduction, and operational reliability.  With this in mind, Pepperl+Fuchs developed a line of products that use the tiny G10 housing.  This includes passive devices- devices that either do not have any electronic components inside or do not require an address on the network- as well as active components like input and output modules.

G10 housing AS-InterfaceThe power of the G10 housing is due to a few unique design features:

  • Size - The G10 housing is small. In fact, with a footprint that is only about as large as two postage stamps, it is the smallest such housing on the market. This means it is easy to mount in the tightest of spaces. And since it is so small, many times it is not even necessary to mount it at all. Connect it to the flat cable and drop it in the cable tray; we call this Connect & Done.
  • Ingress protection - When it comes to providing a superior IP rating, smaller is definitively better. The G10 module is rated IP68/69k mainly because of the contoured seal around the piercing needles. Since they are small, the closing force of the housing is concentrated at a small area. This means the seal pressure is high, ensuring that water has a hard time sneaking by.
  • Convenience - The G10 module is a tremendous improvement when it comes to convenience and handling simplicity.  Compared to larger, two-piece solutions that tried to address the same needs a few years ago, the G10 housing offers a single-piece design.  This means that there are no loose parts, separate gaskets, extra screws, or tops and bottoms that need to be matched- nothing to lose, nothing to assemble. Connecting a G10 device to the flat cable is trivial.  Open the hinged module, insert the cable- we offer solutions that operate with just the yellow AS-Interface network cable as well as solutions that handle both yellow and black AUX cable- close the top, and secure it using the center mount screw. This literally takes only a few seconds.

If you have never seen a G10 device in operation, check out these three short videos:

The first video shows you how to repair a damaged section of network cable using the G10 BRIDGE.

The second video shows you how quickly a network branch for both the network and AUX cable can be added.

The third video shows how easy it is to add just about any other AS-Interface device with M12 connections or terminals.

The G10 at work

In certain industries and applications, it is quite common to protect the main network trunk from overloading when the drops to field devices short out.  One way to accomplish this is to equip the passive G10 devices with integrated PTC overload protection. If the cable is damaged and results in a short, or if the end device ever fails and draws current that is above the PTC cutout, then the PTC inside the G10 housing disconnects the drop electrically from the main network, allowing the remaining components to keep operating.

While the passive devices are incredibly useful, engineers always want more, and our customers challenged us to design a line of full-featured I/O modules in the smallest housing possible. This was, of course, not a minor task, but in the end, our engineers managed to squeeze everything needed to build a full-featured module into this tiny housing. Even more, the modules have integrated pigtails such that sensors and actuators can be directly connected; no additional cordsets needed.

While the workhorses of AS-Interface are typically the 4-input and 4-input / 4-output modules, that much I/O was not attainable given the size of the module. But due to its size, fast installation, and integrated pigtails, G10 modules are ideal in situations where less I/O is preferred. Applications include:

  • Last-minute sensors- No matter how well a system is designed and laid out, it simply happens that another sensor needs to be installed during run-off or commissioning.  The G10 is the ideal solution since a version with one pigtail for one sensor is available.  For added flexibility, this module still has two inputs allowing the use of dual-output sensors. 
  • Last-minute output- Just as another input is needed unexpectedly, machine builders find themselves in situations where additional outputs are necessary.  Using the G10 module, it literally takes just seconds to add them. 
  • Conveyor section control- In material handling applications, it is common to have short conveyor sections that are then combined to build large systems.  In many cases, these segments have a photoelectric sensor to detect when bins and boxes enter the segment plus require an output to control the motor or drive of that section. While this application can certainly be addressed using larger input / output modules, a G10 has the ability to reduce ancillary cordsets even further.

The AS-Interface terminator

In addition to passive connection devices and a selection of input and output modules, the G10 housing is used to house a device called a ‘terminator’. A terminator is passive in the sense that it does not possess an address, but it still contains active electronics. To understand what it is and what it does, it is necessary to know that AS-Interface is a technology that does not require the network to be terminated. Termination is very common among industrial bus systems and required for several reasons; one of them is the elimination of signal reflections at the open end of the network.

For network segments up to 100 m, AS-Interface should never be terminated. In fact, segments should never be longer than 100 m. But occasionally, this not possible or installers simply lose track of the total length of the segment. In those cases, users have two choices.  The "cleanest" solution is to divide the segment in two, coupling them with a repeater. The terminator offers a fast and potentially lower-cost alternative with a high probability of success. If the segment is essentially linear, with a few short drops, the terminator can be applied at the open end of the network. The terminator is designed such that it eliminates or at least reduces cable-end reflections to such a degree that communication is possible.  There is, of course, a limit, and terminators work best if the segment is not too much out of specification, i.e., not too much longer than the 100 m segment limit.  The more severe the violation, the less likely it is that the terminator will work, and pushing it over 200 m is potentially quite risky.

As a general rule, when using a terminator, the communication quality of the network must be evaluated before concluding that it works and it is not necessary to apply a repeater. For a lot more detail on how long AS-Interface networks can be, read our blog "How long can an AS-Interface network really be?"

Placing the terminator hardware into the small G10 housing that is easy to mount and offers exceptional protection makes a lot of sense. Better yet, since the G10 housing offers two cable trays, our engineers designed the terminator with two sets of electronics. This provides additional power and flexibility and allows this terminator to be used in situations where other designs are no longer able to function properly. In order to provide additional feedback, the G10 terminator measures the network voltage and indicates it with bright LEDs.

Safety

But our engineers did not stop there.  There is one other class of AS-Interface applications that can benefit greatly from such a small, easy-to-use housing.  Safety at Work is the safety-rated technology that allows AS-Interface to transport and process safety information from e-stops, protective door switches, light curtains, and more. Safety applications literally begged for the G10 module.

Before the release of the G10, users had only two choices when connecting (for instance) e-stops:

  1. Conventional e-stops equipped with two redundant safe dry contacts are connected to a safety-rated input module. These modules are mounted to the machine- if they offer sufficient ingress protection- or are located inside of small junction boxes.  But in any event, additional space is needed and mounting is necessary.
  2. More recently, AS-Interface providers developed e-stops with integrated electronics. Connecting these kinds of e-stops to a network is, of course, much simpler. All one has to use is a passive G10 splitter with pigtail.

But e-stops are a funny business. They are visible and they are mechanical and many machine owners demand a certain look and feel. But what if that look and feel only comes in a non-AS-Interface enabled package?  There is always option one, but that is significantly less convenient than option two. By designing the safety electronics into the tiny G10 housing, machine builders can finally take any dry contact e-stop (or any other dry contact safety device), and give their customer the look and feel they demand without having to mount a larger safety module.

Think about it, at first glance an intelligent e-stop connected with a G10 passive splitter to the flat cable is indistinguishable from a conventional, dumb e-stop made smart using the G10 safety module. And since it comes with a non-safe output, using illuminated e-stops is also possible.   If you want to read more about when this approach makes sense and where it might not be the best solution, read our blog "The Pros and Cons of AS-Interface Safety Devices."

This discussion started with the statement that "AS-Interface is all about simplifying the designs of a control system, reducing the complexity of the wiring, cutting the cost of the installation, improving diagnostics, and ultimately making automation more productive."  The incredible G10 housing and the many active and passive solutions derived from it are certainly just the beginning.  Who knows what our engineers will come up with next?

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