Moving to make the Modbus protocol a “real” open standard, rather than a “de facto” standard, Schneider Electric has transferred its copyright of the protocol to Modbus-IDA, a nonprofit organization formed in 2002 to advance industrial communications. Modbus was originally developed in 1979 by Modicon—which later became part of Schneider Automation (now Schneider Electric), and is now widely used throughout the world.
The agreement was signed on April 12, 2004, and publicly announced at the Hanover Fair trade fair in Germany. It transfers the protocol to Modbus-IDA, including the entire “right, title and interest” in the protocol copyright.
According to Ken Crater, Modbus-IDA president, the organization intends to pursue international standardization of the protocol. Other goals of the organization are to compile an interoperability catalog of devices using Modbus and to lead the evolution of the protocol into future uses.
Diego Arces, Schneider Electric product manager and Modbus-IDA board member, adds that although Modbus was widely used in the industry and documentation became freely available, it was still owned by Schneider Electric. The “de facto” nature of this standard naturally led to interoperability issues. Transferal of the protocol to an independent organization will permit standardization and compatibility testing, assuring users that Modbus devices will be interoperable.