ATM Modernization, Business & GA, Commercial, Military

Simplifying Databus Analysis

By Charlotte Adams | May 1, 2000
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Mil-Std-1553 databus analysis tools, used to observe bus traffic, identify problems, or verify bus performance, are daily becoming more capable, as well as more complex. While analysis, in the narrow sense of the term, refers to the host system’s ability to examine and display data–with an emphasis on the depth, granularity, and ease with which users can tailor parameters and displays–user software often offers complementary simulation and monitoring capabilities.

Software capability depends on both the logic elements in the host computer and the individual 1553 boards. Bus cards come in an array of standard formats, such as ISA, PCI, half-sized PCI, compact PCI (CPCI), the miniature PCMCIA, and VME/VXI. High-speed (sometimes multiple), general- and special-purpose processors crowd these circuit boards and are regularly upgraded. Multiple 1553 cards can be installed on a user’s host computer, with performance limited by the host’s ability to service the cards and archive the extracted data, explains Bill Schuh, SBS Technologies Inc.’s director of new product business development.

Competition is keen and each player stresses a different feature set. Some of the participants include SBS, Excalibur Systems Inc., Data Device Corp., Tech S.A.T., AIM GmbH, and SCI Systems Inc.

The Hardware

SBS Technologies Inc.
SBS ( offers 1553 cards compliant with its new PASS-3200 Protocol Analysis and Simulation System in ISA and PCI formats, Schuh says. (A 3200-compliant PCMCIA card was planned for release in March.) The PCI and ISA units offer one or two dual-redundant channels, plus one DSP per bus per channel and field programmable gate array (FPGA) support.

Data Device Corp.
DDC ( ) is introducing a range of new PC-based 1553 cards, including PCMCIA (available now) and half-sized PCI (expected by late second quarter), supported by Windows-based software, says Mike Glass, databus products applications manager. DDC also expects to release a VME/VXI 1553 card by the end of the third quarter, with parallel NT and VXWorks software support.

The PCMCIA card, with an on-board DSP, features one dual-redundant 1553 channel. The half-sized PCI card will include one or two 1553 buses, with one on-board DSP per channel. The new VME/VXI card will provide up to four dual-redundant channels, with similar DSP support. Both the half-sized PCI and VME/VXI cards support direct memory access and global time stamping.

Excalibur Systems Inc.
Excalibur ( offers: 1553 ISA cards with one dual-redundant channel and up to eight dual-redundant channels; full, single-channel PMCIA; up to two-channel, compact PCI; and up-to-four-channel PCI cards. The eight-channel-capable card, with one UTMC 1553 hybrid processor per channel, provides single-function, bus controller, remote terminal or bus monitor capability.

AIM ( provides PCI, half-sized PCI, and compact PCI 1553 cards supporting bus analysis, simulation, test, and data acquisition. The PCI card provides two, dual-redundant channels, while the half-sized PCI and compact PCI cards support a single bus stream. AIM supplies one RISC-based support processor per card, plus one RISC protocol processor per channel. All cards operate with the company’s PC Bus Analyzer 2000 (PBA 2000) software.

Tech S.A.T GmbH
Tech S.A.T ( offers a single, dual-redundant-channel, VME/VXI card, with three on-board MIPS R3000 processors. The board operates in the company’s Avionics Development System 3000 (ADS 3000) data, acquisition and analysis environment.

SCI Systems Inc.
SCI Systems Inc. ( provides a dual-channel VME 1553 card, comparable to the hardware that customers are flying. The unit is available, with basic software subroutines, to avionics customers who build higher-level applications themselves, explains Malcolm Bounds, marketing manager. The card includes bus controller, multiple remote terminal/monitor and diagnostic modes, as well as error injection and detection.

The Software

Software analysis tools provide flexibility, customization, and ease of use in setting parameters, viewing data, and generating reports. SBS’s Windows-based PASS-3200 software can operate up to eight 1553 channels concurrently. SBS ISA and PCI cards, plus the forthcoming PCMCIA card, support full analysis capability, including playback with errors–even bit errors–as they occurred, and the ability to loop playback of an archive file continuously, Schuh says.

Key features that can be displayed include: percent of bus loading; primary and secondary bus activity; remote terminal activity histogram; bus count analysis; user-configurable intermessage gap time; message number and direction; individual remote terminal errors; and remote terminal complex and external triggers. (The user can chain a number of conditions together in order to trigger the monitor function.) The bus controller editor can also be set up to perform up to 16 transmit retries on bus A and B. Users can create, simulate and monitor fully-loaded buses, including all remote terminals and subaddresses, concurrently, he adds.

DDC offers Windows 95/98/NT software and tools, along with its new hardware–so far, in the PCMCIA form factor–including menus and runtime libraries. Users can access bus controller, remote terminal and monitor functions through an improved graphical interface and can conduct concurrent bus playback and monitoring. The host computer can support up to four half-sized PCI cards, each with two 1553 channels, plus two single-channel PCMCIA devices. Previously developed applications can be recompiled and used with the new card.

"The ultimate challenge is not the MIPS [millions of instructions per second], but keeping up with the bus traffic and processing data at the fastest speed sent by the bus," says Mark Kozikowski, DDC’s senior software applications engineer. The platform can handle both the minimum intermessage gap and higher-level capabilities without functionality loss.

Excalibur cards use monitor, analysis and retrieval system (dataMARS) and simulation (dataSIMS) software from Ampol Technologies Ltd. ( ). The analysis software allows presentation of data in engineering units and allows users to configure automatic storage initiation and termination via triggers.

Through the user interface, engineers can create customized meter, gauge, and bar-graph displays that make it easier to spot anomalies on the bus, says George Sponsler, director of sales and marketing. These tools can be displayed dynamically as recorded data is played back. Data can also be exported into Microsoft Word or Excel for immediate generation of flight test reports.

Powered by the additional on-card processing power, the AIM PBA 2000 bus analyzer system can reconstruct the physical bus data–replaying the bus electrically–says Doug Ullah, director of international sales and marketing. This means bus traffic is replayed exactly as it came across, without losing any timing or other characteristics. There is "no performance degradation with [bus] replay and reconstruction," Ullah says.

PBA 2000 also provides a common time stamp that can be fed to all boards to synchronize them to a common source, he says, allowing accurate reconstruction of multiple buses and the interaction between them.

Competitor Tech S.A.T. offers a Unix-based ADS 3000 hardware/software system, which features the recording, and then replaying, of 1553 signals across all 1553 cards, with common time tags. The system also can record, and then replay, general-purpose, non-1553-specific analog and digital signals.

Users can simulate bus controller, monitor, and all remote terminals simultaneously, with error detection, error injection, timing analysis, and common time stamping–at 1-microsecond granularity–says Tech S.A.T. president Bruno Schlecht. NASA’s International Space Station uses a 24-card system to record, play back, and analyze all space station 1553 traffic, he notes.

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