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Responding to proposed revisions that threaten the integrity of the IEEE-488 standard -- a worldwide, reliable communications standard for data transfer -- Hewlett-Packard Company today announces its strong opposition to the changes and urges members of the Institute of Electrical and Electronics Engineers (IEEE) to vote against the changes in an upcoming ballot. Joining HP are Keithley Instruments GmbH, Germany; ines, Inc., a research and development firm providing GPIB interface cards; and ACEA, a T&M development company in Wierden, Netherlands.
The proposed revisions, known as "High-Speed-488" (HS-488), constitute a radical change to the function and form of IEEE-488 (known as IEC-625-1 in Europe) and, according to HP and others, could lead to disruptive errors for the installed customer base. HP has objected to the HS-488 proposal since 1992.
"Customers around the world depend on the integrity of products tested with the IEEE-488 standard," said Ned Barnholt, HP senior vice president and general manager of the Test and Measurement Organization. "Members of standards committees know that when the industry considers changing a standard, a huge amount of interoperability testing needs to be performed. The proposed revisions have not been adequately tested on-site, especially for noise immunity and interoperability, and very little documentation of such testing has appeared in the technical media."
Karl Sasgen, business unit manager for Keithley, said, "Our customers like the ease of use, flexibility and wide range of products to choose from among the existing IEEE-488 bus standards. With the proposed HS-488 protocol, setting up a system becomes more difficult, less flexible, and the customer has fewer products to choose from. And incompatibilities with existing systems are unavoidable. This is too high a price to pay for the marginal overall speed increase of about 10 percent."
Designers, developers and application specialists rely on the historically flawless operation and consistency of IEEE-488 to free them to spend time designing and configuring test systems rather than trouble-shooting performance problems and dealing with erroneous test results. The standard''s three-wire handshake provides reliable synchronization of data transmission over the bus in even the harshest and noisiest settings.
Of paramount concern to HP and others is that HS-488 circumvents the IEEE-488 three-wire-handshake protocol and could compromise the standard''s robustness, resulting in spurious noise, loss of data and loss of data error detection. HS-488 offers a two-wire handshake protocol, which has not been proven effective in ensuring data integrity and has not been shown to be adequately tested in the field, especially in noisy environments.
"Increased bandwidth is directly proportional to increased noise," said Jerry Mahabub, senior systems engineer for ines, Inc. "The three-wire handshake addresses this problem and ensures that the transfer of data is flawless by utilizing three byte-transfer lines to coordinate data transfer on the GPIB bus from a source [the addressed talker or controller] to an acceptor [the addressed listener, that is, all instruments receiving IEEE-488 commands]. The two-wire handshake makes only a minimal effort to guarantee data integrity."
HP believes that increased data rates are better addressed using emerging PC-based standards such as USB and Firewire, which have undergone significantly greater interoperability testing than the changes proposed in HS-488. "USB is an accepted computer industry standard that provides great flexibility at low system costs," said Dave Richey, engineering manager for HP''s Measurement Systems Division. "Firewire also shows great promise and offers far greater bandwidth than the proposed revisions. Why should our industry commit huge resources to a questionable extension of IEEE-488 when the computer industry is already developing excellent solutions for increased speed?"
John Pieper, managing director of ACEA said, "IEEE-488 was designed specifically for simplicity of implementation and ease of use in a wide variety of applications in stable or changing configurations. The proposed enhancement would seriously compromise the entire domain of 488 applications and developments." (The ACEA Web site, http://ourworld.compuserve.com/homepages/acea, provides additional information on this issue.)
Richey said that while HP is not against revising a standard if doing so would result in benefits for installed-base customers, HP does oppose revisions that could well lead to unanticipated problems, unnecessary expense and vendor interoperability issues. HP is respectfully requesting that the proposal to modify this standard be abandoned.
Invitations to ballot on revising IEEE-488, titled "Standard for Higher Performance Protocol for the Standard Digital Interface for Programmable Instrumentation," already have been sent out. The actual date for members to cast their ballots has not yet been announced, but is expected to take place within the next 12 weeks.