Modbus protocol is accepted by IEC as a Publicly Available Specification

Sept. 27, 2004
Sept. 27, 2004 - Variant of the protocol was submitted to the IEC as an industrial Ethernet suite.

The ubiquitous Modbus protocol, whose ownership was recently transferred from Schneider Automation to an independent nonprofit organization, Modbus-IDA, has been accepted by the IEC as a Publicly Available Specification.

The TCP variant of the protocol, along with a companion protocol known as RTPS, were submitted to IEC SC65C as a real time industrial Ethernet suite. The submission was made possible by the recent granting of a type D liaison status to Modbus-IDA by the IEC. Of 25 countries voting on the proposal, there was only one negative vote, reflecting overwhelming approval of the specification. At the same time, the specification was
accepted as a New Work Item by the subcommittee.

"We are delighted to be the first PAS to be approved during this submittal period," says Modbus-IDA President Ken Crater. "Although our organization is quite new, this approval reflects the outstanding acceptance that Modbus has received in the industrial
marketplace over the past 25 years. More significantly, however, this Publicly Available Specification represents our organization's dedication to bringing a new level of
openness to industrial communications."

In approving the document, several national committees asked for a reformatting of the specification to allow for better integration into the revision of IEC-61158 (Ed 4.0 2007), the well-known fieldbus standard. According to Crater, Modbus-IDA intends to make this reformatting a priority for the organization.

"MODBUS, the only industrial messaging protocol already recognized by the Internet world (port 502) has one of the largest installed bases worldwide with more than 7.2 million installed nodes," says Jean-Jacques Poubeau, vice president of Major Programs at Schneider Electric and a Modbus-IDA board member. "With this positive vote, the MODBUS TCP-IP profile has been accepted by the IEC as a Publicly Available
Specification and is now eligible to become part of future editions of the International Standards IEC 61158 and IEC 61784-2. This is a significant step forward for the efficient, proven and cost effective Industrial Ethernet solution supported by Schneider Electric."

The agreement transferring the Modbus protocol to Modbus-IDA was signed by Schneider Automation, Inc. on April 12, 2004 and was publicly announced that
month at the Hanover Fair trade show in Germany.

Modbus-IDA, the international organization for suppliers, implementers and users of the Modbus protocol and its variants, is based in North Grafton, MA. For more information visit

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