Method and apparatus for testing systems that communicate over digital buses by transmitting and receiving signals in the form of standardized multi-bit binary encoded words

摘要

An apparatus is disclosed for testing line replaceable units (LRUs) of an avionics system in which the various units of the system exchange information by means of transmitting and/or receiving digital communication words, each word having a predetermined, standardized format. In a transmit test mode of the apparatus, the information content of a test word is formulated in either engineering or binary form by using a keyboard to create the word manually, or by retrieving a preprogrammed word or sequence of dynamically changing words from a plug- in programmable read only memory (PROM). Once formulated and stored, the communication word is repetitively transmitted, at selected word and bit transfer rates, from one or more output ports provided on the test set and applied, by a jumper connection, to a data communication bus that, in turn, is connected to one or more avionic LRUs. A CRT on the control panel of the test set simultaneously displays the information content of the transmit word, both in engineering and binary form. In a receive mode, a signal receiving port is coupled to a communication bus associated with one or more avionics LRUs for monitoring preselected communication words that are exchanged between the LRUs connected to that bus. The received word or words are decoded by the test set and displayed both in engineering and binary form on the CRT. The transmit and receive modes may be used concurrently so that a given LRU or groups of LRUs can be stimulated by one or more transmit words, and the word responses of such LRUs monitored. In a further mode, called receive-all, an abbreviated form (LABEL) of the engineering notation of each word present on a monitored data bus is displayed on the CRT, allowing the user to select certain words from among the displayed LABELs for full-word processing in the above- mentioned receive mode.