This part of IEC 62026 specifies an interface system between single or multiple controllers, and control circuit devices or switching elements. The interface system uses two twisted shielded conductor pairs within one cable - one of these pairs provides a differential communication medium and the other pair provides power to the devices. This part establishes requirements for the interchangeability of components with such interfaces.
This second edition of IEC 62026-3 cancels and replaces the first edition published in 2000. This second edition constitutes a technical revision. The main changes with respect to the previous edition are listed below:
- addition of new services to the base messaging protocol in 5.2;
- replacement of detailed application layer requirements in former annexes by references in 5.3 to corresponding specifications in the new edition of IEC 61158 (2007);
- addition of requirements for a corresponding safety protocol in 5.6 (by reference to IEC 61784 3);
- modified presentation of cable and connector specifications in 8.2 and 8.4, and addition of a new type;
- addition of references for safety tests for both EMC and logical tests in 8.10 and 9.3).