Stressing Flexibility

By Charlotte Adams | September 1, 2000
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Although the Mil-Std-1553 spec, after decades of use, is ancient as electronics standards go, designers continue to develop cards and software, using the latest technologies. Bus analysis software, employed to monitor bus traffic and isolate problems, addresses complex systems integration problems, as well as difficult communications issues. Designers squeeze hardware resources into ever-smaller packages, and efforts focus on flexibility–multiple ways of viewing and manipulating 1553 data.

Condor Engineering and Ballard Technology are adding new levels of flexibility and convenience to bus analysis. Meanwhile, newcomer, PowerCom, an 18-month-old joint venture between Leach International and P&R Engineering, recently unveiled a half-sized ISA (industry standard architecture) PC 1553 interface card and analysis software. (P&R has 15 years of aerospace market experience, but not as an independent bus card and analysis software vendor.)

PowerCom seeks to break into the market, not only with capability, but with price. "Mil-Std-1553 is a premium market–products are sold at a premium price," says Brian Ross, national sales and marketing manager. PowerCom sells single-bus cards for below $2,000, compared to the typical asking price of $3,000 to $3,500, he says. Its dual-bus cards sell for less than $3,000, compared to $6,000 and up elsewhere, he contends. PowerCom plans to release a PCI (peripheral component interconnect) card soon.

In Bus Controller Mode

Test cards and software can address a range of problems. The cards are often set up in "bus controller" mode to communicate with avionics boxes and test their responses. (In 1553 technology, the bus controller directs traffic, sending commands to devices–or remote terminals–to transfer data on the bus.) Smiths Industries built a tester using a Ballard 1553 PCMCIA card. The card operated as a bus controller, interrogating built-in-test software in Smiths Industries’ box, a pylon interface unit on the Apache helicopter, says David Christmas, a Smiths project engineer. Ballard’s card sent messages to the helicopter unit and told the box to send messages back, "to see if everything was working okay," he says.

In a less common application, Honeywell used a Condor PC card and software to act as a third party, monitoring bus traffic between an aircraft black box and test equipment for the box. Engineers wanted to determine whether the black box or the tester itself caused a certain problem, a very difficult task, says David Levine, a senior staff engineer with Honeywell’s Aerospace Engine and Systems division.


Condor Engineering and Ballard Technology offer a range of 1553 test and simulation boards in various formats, but recently have released families of small-format 1553 cards. Condor’s 3U CompactPCI (cPCI) card fits into a 6-inch (15.2-meter) tall chassis, giving test setups a smaller footprint. Ballard’s new line of credit card-sized PCMCIA 1553 test cards fit into a notebook computer. PowerCom has introduced a half-sized PC ISA board and plans to release a PCI board in the near future.

Condor’s 3U cards offer: single- and dual-bus, multifunction boards and single- and dual-bus, single-function boards, says vice president Bill Weil. The multifunction card can simulate bus controller, up to 31 remote terminals, and bus monitor at the same time, he says. The simpler, single-function bus card simulates the bus controller, or the 31 remote terminals, or the bus monitor. (A bus monitor, used in off-line applications, is a terminal that listens to data communications on the bus.) Condor also offers 1553 cards in the PCI, VME and other formats, and is developing a larger, 6U version of the cPCI card.

Condor’s new cards use a processor "specifically optimized for 1553," Weil says. It can process "thousands of messages per second," he adds. Cards also feature 1 megabyte (1 million bytes) of memory per bus.

Ballard offers four levels of PCMCIA cards. The basic "A" level functions as one terminal at a time–either as a bus controller, bus monitor, or remote terminal, says Kevin Christian, customer services manager. The next level up (known as "B4") allows engineers to simulate up to four terminals, and the third level ("B32") allows up to 31 terminals (or a bus controller), he explains. At the top, the "C" level simulates all remote terminals, bus controller and bus monitor. Ballard employs standard, high-speed, digital signal processors made by Texas Instruments on its PCMCIA cards. The company offers the same electronic core across its PCI, cPCI and standard, desktop-PC (ISA) cards.

PowerCom’s first 1553 product is a 16-bit, half-sized ISA board with up to two, dual-redundant buses. The card can operate as a bus controller, talking to an external box, or a monitor terminal, observing traffic, or a combination of a bus controller and remote terminal. PowerCom expects to introduce a PCI card with similar functions shortly. The company also plans to introduce a tester/simulator card next year.


Condor: Condor’s BusTools graphical user interface (GUI) offers features supporting applications from simple communications to system integration, Weil says. "System integration is a whole new field for 1553 bus analyzers," he adds. In a system integration problem, there could be multiple boxes, all operating differently and all communicating. "You have to make sure that they are all seeing the right data."

Condor offers different levels to look at the data, such as "selective data watch" and "parallel analysis." The parallel analysis tool lets technicians look at multiple messages in parallel, while selective data watch allows an engineer to look at data words–components of a data message. Another feature allows users to remove data on one remote terminal from the recorded traffic and insert data from a different box, to see how a new box responds against real bus data.

BusTools also allows engineers to import data definitions into the analysis program and convert raw 1553 input into the data values used in a real-world application. (The fifth word in a 1553 message for an avionics box may refer to altitude, for example, and be expressed in feet.)

Ballard: Ballard’s CoPilot supports five views of bus data–from a "form view," showing messages with all the data words, to a detailed message view, showing the origin of the message, the command and status words, and detailed timing information, Christian says. Bus monitor filters can be set wide open to collect all of the data, or more narrowly to highlight a few terminals or display messages to a single terminal subaddress. (Each terminal has up to 32 subaddresses.)

Users also can "edit out" terminals and put in simulated data, thus combining real and simulated data. A "one-shot" message transmitter function allows engineers to create and transmit a test message in four mouse clicks, Christian says.

PowerCom: PowerCom’s DataCom 1553 software offers real-time data displays and status displays, showing bus activity and message processing, says David Iser, a software development engineer. Whereas most analysis products save data in a text file, DataCom saves the data in a database file that is easier to search, Ross adds.

The analyzer software is designed to support the Microsoft Access database, he says. "You can search for data going across certain addresses or look for a specific environment of data."

DataCom also features a "virtual port interface" for flexible data input and output, Iser says. The port provides an interface so that data from sources such as test environments, text files, and computer serial buses can be entered into the PowerCom program and then sent out onto the 1553 bus.

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