The current version of IEEE 1641 was approved and published by the IEEE in 2010. Its formal title is "IEEE Std 1641™–2010, IEEE Standard for Signal and Test Definition." It is a revision of the original version of IEEE 1641 that was published in 2004.
IEEE 1641 is a test language that is used for the specification of test requirements and test programs. Its key underlying principle is that all its test signals are supported by a mathematical foundation. IEEE 1641 is based on a set of primitive components or "Basic Signal Components" (BSCs), which are used to form the basis of all other signals. These BSCs are combined to form higher level signals, and so on, upwards. The higher level signals may then be grouped into libraries according to project requirements.
IEEE 1641 has a hierarchical structure with the lowest layer (the mathematical definitions) supporting the BSCs. The BSCs are then used to support the next level up; Test Signal Frameworks (TSFs), which are reusable test signals that are used in test programs to define the actual signals applied to (or expected from) a test subject. TSFs are usually assembled into libraries of related signals. Libraries may be technology dependent, project dependent, unit under test (UUT) dependent, or any other convenient grouping.
The highest level is the test requirement itself, which may be expressed in several different forms. The basic format comprises 1641 signals within a carrier language – the carrier language provides the sequential information and "carries" the signals. The carrier language may be of the users choice, provided that it complies with the requirements of the 1641 standard. The signal information is most often expressed in XML, i.e. each signal to be applied or measured is described in XML and is interspersed within the carrier language code. The process of creating such test requirements will normally be controlled using a tool-set that automatically produces the XML signals and probably the carrier language code from a higher level graphical interface.
IEEE 1641 includes its own Test Procedure Language (TPL), which is an ATLAS like textual language, that may be used to express the application and removal of signals. TPL still requires the use of a carrier language, and adds a further process into the implementation of IEEE 1641 programs. TPL is of particular use where a 1641 capability is added to a legacy ATLAS based system.
The test requirement may also be defined using ATML's Test Description standard (to give it its formal definition – IEEE Std 1671-1, IEEE Standard for Automatic Test Markup Language (ATML) for Exchanging Automatic Test Equipment and Test Information via XML: Exchanging Test Descriptions). This standard provides a schema for describing test requirements using a standard XML format, and also uses IEEE 1641 for defining the signals themselves. More information about ATML is available from the ATML website.