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Thursday, December 1, 2011

Databus

Tried-and-true Mil-Std-1553 databus systems remain popular options for next-generation aircraft due to their reliability and high performance

By Ed McKenna

Even as they deploy networks on new aircraft to support high-speed systems, aircraft designers are increasingly looking at Mil-Std-1553 databus technologies to support their mission critical systems.

This interest in the old, but reliable, military standard is being driven by the technology and design changes in the next-generation aircraft and ongoing efforts to reduce weight and, in some cases, address security risks.

Eyeing these market developments, technology providers are devising innovative products including smaller, more capable 1553 databus systems designed to bridge the divide between different systems used on commercial and military aircraft.

The resilience of 1553 standard is by no means a new story. “The death of 1553 has been predicted for the last 20 years and, of course, it has never happened,” said Roy Nardin, data bus product line manager with National Hybrid, Inc. (NHi), based in Ronkonkoma, N.Y. Around since the 1970s, “1553 is never going away,” he said.

Airbus’s decision to adopt 1553 for its A350 flight critical systems put the “stamp of the dependability and reliability” on the standard, said Steve Holder, global avionics sales manager, GE Intelligent Platforms. The Charlottesville, Va.-based company sold the development gear for those systems to Airbus, he said.

The standard is also being used on China’s COMAC C919 narrowbody aircraft, and Boeing is looking at it for its next-generation aircraft, said Harry Wild, vice president of sales of Rio Rancho, N.M.-based Alta Data Technologies, a company that offers 1553 components including a new product that bridges 1553 and Ethernet systems.

The standard’s strengths play well in an era in which aircraft are using fly-by-wire controls and composite fuselages. Compared to commercial ARINC 429 standard, it has “lower error rate and high noise immunity,” Nardin said.

Designed for critical systems on military aircraft, Mil-Std-1553 systems have proven their mettle “over the years in military operations supporting systems that control weapons, surfaces elevator … (and) engine control, data monitoring, navigation.”

“Mil-Std-1553 is an extremely robust physical layer … (and) very deterministic,” said Sean Sleicher, marketing manager, data bus products with Data Device Corp. (DDC), based in Bohemia, N.Y. Along with its proven operational record, these attributes were very attractive to Airbus, which will be using 1553 for “specific applications like power distribution, power management or controlling the flight surfaces,” said Sleicher. DDC was selected in 2010 to supply 1553 components for the A350’s flight control system.

National Hybrid’s plastic ball grid array 1553 terminal is being designed into the rudder control system of the A350.

EMI protection was the critical factor in Airbus’s decision. Mil-Std-1553 boasts “superior EMI performance,” said Chris Stabile, marketing communications manager with DDC. With lightweight, composite fuselages, the new generation aircraft “are more susceptible to lightning strikes getting actually through (unlike) … the aluminum aircraft,” he said.

Finally, the standard’s multi-drop bus setup offers a weight advantage over ARINC 429’s “one-to-many” layout which has “one transmitter talking to up to 28 receivers” requiring a lot of discrete wires. “That adds a lot of weight and complexity,” said Sleicher.

The standard’s Achilles heel is its speed. “One of the reasons they were predicting the death of 1553 is because it is a one megabit per second Manchester encoded serial data bus,” Nardin said. That rate stands in stark contrast to the 100 Mbps Ethernet systems being deployed on commercial and military aircraft to handle the growing number of video-rich applications.

“Clearly for certain applications there are needs for increased bandwidth, and in those cases the 1553 is not going to be the right choice for you,” Sleicher said.

In the case of A350, designers addressed the speed issues by using Avionics Full-Duplex Switched Ethernet (AFDX) to handle high-speed video systems with 1553 handling the critical systems. The 1553 bus is also “limited to 32 items at most and 32 remote terminal addresses, and of those you only have 32 sub-addresses and 32 words; in each of 16 bits you can have about 900 or 1,800 pieces of information,” said David Garcia, vice president of marketing and sales with AgiLynx, of Billerica, Mass. “You can do a lot with that, but not everything on a modern system.”

Even with these shortcomings, “I can see why Airbus made their decision,” said Garcia. ARINC 429 “is a one transmitter multi-receiver (setup), so it is very point to point … (and) not a very convenient way to wire up an airplane … and units … have to have multiple inputs to talk to multiple units, so it is very disorganized.”

That said, ARINC 429 remains the dominant commercial standard by a wide margin and will for years to come, industry officials concede. That fact provides a clear niche for a product like the AgiLynx Lynx Protocol Converter. The product provides a data bridge between1553 to 429 allowing, for example, military aircraft that run on 1553 to add COTS products. “Our product can actually connect with a bus monitor, bus controller or a remote terminal, so it can do all of the three of the functions on a 1553 type of terminal,” Garcia said. In addition, the component “can be configured without a new software configuration because the configuration is an input to the unit, so we certify to all possible inputs.”

Addressing another standards divide, Alta Data Technologies has introduced eNet-1553, which allows for “remoting” of 1553 operations on 10/100/1000 Ethernet IP/UDP local area networks. To ensure the reliability of the data, the company has “developed a handshaking technology that allows you to make sure that every data packet is received and … we also message and time tag all of our data packets,” Wild said. “Because we are dealing with an asynchronous 1553 bus communication (running) over a nondeterministic Ethernet, we timestamp each one of our data packets down to 30 nanoseconds.”

“We have about a half-dozen embedded system designs that are in process some of them are extremely large for the U.S. Army, Lockheed, Goodrich and Boeing,” he said. “Right now we are still in the development phase for the product … (but) expect to actually be in flight next year with this product on military and commercial (platforms).”

AgiLynx and Alta Data are but two of the many companies developing technologies for broad market associated with the Mil-Std-1553. These products are targeting different with a wide range of designs and form factors. For example, several companies have developed higher speed 1553 products. Edgewater Computer Systems, of Ottawa, Ontario, said its Extended 1553 technology garnered a great deal of attention initially touting potential speeds up to 200 Mbps. DDC has developed high-speed options including “Turbo-1553 and HyPer-1553 that can actually have the same 1553 physical layer at 200 Mbps potential,” said Stabile.

NHi offers a 2 Mbps 1553 bus that “does everything that 1553 does at twice the speed” and can run on the same cables as the standard 1553 bus, Nardin said. Using the two speeds, a developer could conceivably double the number of terminals on the databus with the addition of 30 2-Mbps terminals on the bus, he said.

To date, efforts to market the higher speed buses seem to be yielding mixed results. Edgewater’s efforts to market at least the very high-speed 1553 took a hit when the U.S. Air Force abandoned its plans to develop aircraft databus technology that operated at 200 Mbps. Nardin reports some European customers are looking at NHi’s faster bus but “over here they are not jumping up and down about it, but I think in the future they may be looking into it to get it to run faster” and add the capacity.

The need for the higher speed buses on aircraft is limited because “there are other technologies out there, such as AFDX, that fill that bill,” said Holder. However, there is a need for the higher speed versions on missiles “because they are flying at higher speeds and need the update rate and … to be able to change direction quickly,” he said. “We have helped to develop a 10 Mbps (bus), and we sold it into particular missile applications.”

Along with speed, developers are reducing the footprint of their offerings. DDC rolled out its Total-AceXtreme compact Mil-Std-1553 interface this year. It combines transceivers and transformers –– formerly separate components with the protocol and memory into 0.63 by 0.63 by 0.185-inch package “the smallest complete package available today in the world,” said Stabile. It includes a newly designed, more power efficient transceiver that previous parts had.

With an eye towards size reduction, developers are increasingly focusing on Mini Peripheral Component Interconnect Express (PCI-e) cards. For example, DDC developed a Mini PCI-e card “that is smaller than a gum stick” on which “we were able to fit two channels of 1553,” said Sleicher. It is the “only Mini PCI-express card that has two channels.”

Alta Data recently released a single channel Mini PCI-e. Holder said GE Intelligent Platforms is now “offering low profile PCI product … and is looking at Mini PCI-e also.”

NHi is giving its customers choice between two products Terminal+ and Bus+ that combine terminal and transceiver in a single package, said Nardin. Terminal+ is designed for users looking for “the whole plug-and-play deal; they don’t have to do anything.” It includes 117 over-sized balls with large pitch to eliminate solder shorting risks and offers a 5V or 3.3V transceiver option, PCI target or local bus interface and dual port, double-buffered 64K by 16 SRAM. In total, Terminal+ measures 1.05-inch by 0.75-inch by 0.185-inch. “We also have what we call our Bus+ which incorporates transceiver and transformer, which people can buy that if they are using IP hook it right up to their IP,” said Nardin. It contains NHi’s proprietary transceiver ASIC and the Pulse 1553 dual ratio transformer.

The company also offers 1553/USB Pocket Pal, which includes a redundant 1553 terminal with 64K words of internal ram. It weighs less than 7 ounces and is small enough to fit into a shirt pocket, and when it is plugged into a laptop via a USB port, it turns that computer into a 1553 workstation. A developer can, after developing application software, load it into the Pocket Pal and “actually test it by putting it on 1553 bus,” Nardin said.

Despite the attention garnered by new aircraft in this market, such as the Airbus 350, most companies are keying in on the military retrofit market as the government curtails spending on new systems. “We have seen an increased desire to retrofit older military aircraft with newer electronics,” such as Terrain Awareness and Warning Systems, said Garcia.

“We are still seeing our business as strong,” said Holder. “The government is (still) investing in UAVs and that market is still using 1553 … We are in numerous UAV platforms including Fire Scout, the Hunter, Global Hawk. In these systems, the technology is installed anywhere from ground station control to embedded on the aircraft,” he said.

Meanwhile, development continues. “One of the test areas the company is looking at now is embedding a Mini 1553 or 429 card on a tablet computer,” said Wild. “We have three tablet manufacturers right now embedding out technology into (their products).”

Next month: Cockpit Switches

Avionics Magazine’s Product Focus is a monthly feature that examines some of the latest trends in different market segments of the avionics industry. It does not represent a comprehensive survey of all companies and products in these markets. Avionics Product Focus Editor Ed McKenna can be contacted at emckenna@accessintel.com.

Companies

Aero Express www.aeroexpress.com
Aeroflex www.aeroflex.com
AgiLynx, Inc. www.agilynx.com
AIM GmbH www.aim-online.com
Airflair www.airflair.co.uk
Alta Data Technologies www.altadt.com
Avionica, Inc. www.avionica.com
Avionics Interface Technologies www.aviftech.com
Ballard Technology www.ballardtech.com
Barco www.barco.com
Beta Transformer Technology Corp. www.bttc-beta.com
Curtiss-Wright Controls www.cwcontrols.com
Data Bus Products www.databusproducts.com
Data Device Corp. www.ddc-web.com
Edgewater Computer Systems www.edgewater.ca
Elbit Systems www.elbitsystems-us.com
Emerson Connectivity https://emersonconnectivity.com
Emteq www.emteq.com
Excalibur Systems www.mil-1553.com
GE Intelligent Platforms www.ge-ip.com
Holt Integrated Circuits www.holtic.com
Hytronics Corp. www.hytronicscorp.com
ITCN www.itcninc.com
Kontron www.kontron.com
LeCroy Corp. www.lecroy.com
MAX Technologies www.maxt.com
Microsemi www.microsemi.com
Milestek www.milestek1553.com
National Hybrid Inc. www.nationalhybrid.com
North Atlantic Industries www.naii.com
North Hills Signal Processing www.northhills-sp.com
Phoenix Logistics www.phxlogistics.com
Raycom Electronics www.raycomelectronics.com
Sabritec www.sabritec.com
Sanmina-SCI Technology www.sanmina-sci.com
Sital Technology www.sitaltech.com
Tech SAT GmbH www.techsat.com
Tepro of Florida www.tepro-vamistor.com
Ultra Electronics www.ultra-electrics.com
Vector GmbH www.vector.com
Western Avionics Ltd. www.western-av.com
YED USA www.yed.com


Market Moves

The following are new products and developments from developers and manufacturers of ARINC 429 and Mil-Std-1553 databus products.

➤ Holt Integrated Circuits in September released the application development kit for the HI-6130 Mil-Std-1553 multi-terminal device. It provides a single-chip, 3.3V BC/MT/RT Mil-Std-1553 system, including dual transceivers and 64K bytes RAM, in a compact surface-mount 100-pin PQFP package. The hardware includes a 2-board assembly, comprised of an upper HI-6130 board with dual transformer-coupled Mil-Std-1553 bus interfaces and a lower microprocessor board with ARM Cortex M3 16/32-bit microprocessor, debug interface and regulated 3.3VDC power supply.

➤ AIM introduced APE429-x, a PCIe module for ARINC 429 test applications, the Freiburg, Germany-based company said in October. The company said four, eight or 16 channel modules are available. Each channel is software programmable for receive or transmit mode and high/low bit rates. It uses a high-speed FPGA with integrated PCI-Express bus (1x Lane/2.5Gb/s) and IRIG-B Time Encoder/Decoder. Integrated in the cards are eight (Avionic Level) General Purpose Discrete I/O (GPIO) signals which can be used to generate strobe outputs or to sample external digital inputs.

➤ Alta Data Technologies in October introduced two products for PCI Express systems: Mini PCI Express MPCIE-A429 and a One Lane, Low Profile PCIE1L-A429 interface card. These products provide shared ARINC-429/575 RX/TX channels and support ARINC-573/717 standard and include a modular software development kit, AltaAPI.

➤ Avionics Interface Technologies (AIT), of Omaha, Neb., in August released a USB test and simulation module for ARINC 429 databuses. AIT’s USB429 is a rugged module designed to provide a stand-alone ARINC 429 interface for avionics applications. It supports up to 16 ARINC 429 channels, each can be individually configured to transmit or receive and to operate at the high or low bit rates defined by ARINC 429. Full error injection and detection is supported, as well as customizable options for label selective triggering. The USB429 enables real-time recording and analysis of multiple channels, according to the company.

➤ Beta Transformer Technology Corp., based in Bohemia, N.Y., introduced the BXC-A-2 two-stub box coupler. This box coupler achieves full Mil-Std-1553 compatibility in system development, laboratory, test and flight line applications.

➤ Israel-based Sital Technology launched PMC Hyperboard, a platform for avionics communication bus applications. It adheres to numerous bus standards including Mil-Std-1553B, H009, WB194 and DigiBus. PMC HyperBoard features eight dual-redundant, configurable channels where each channel can be a bus controller, remote terminal or MultiRT and/or monitor. The board provides 8X avionics and 8X digital discrete I/Os.

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