1. A data gathering system for collecting data from a plurality of analog signal sources, comprising: a digital computer system; means for converting an analog signal into a digital value when supplied with an analog signal address, said means connecting said plurality of analog signal sources to said digital computer system; a plurality of machine readable definitions each defining an analog signal scanning operation, and each specifying an analog signal address and a variable scanning frequency or period; means for operating said computer system to accept and to store said definitions; means for operating said computer system to establish linkages between groups at least portions of said stored definitions such that each group includes portions of definitions which specify the same scanning frequency or period; and means for operating said computer system to process each group of linked definition portions periodically at a rate determined by the scanning frequencies or periods specified by the definitions whose portions comprise each linked group, where processing comprises following the linkages from one definition to the next and carrying out the analog signal scanning operation called for by each definition.
1. A data gathering system for collecting data from a plurality of analog signal sources, comprising: a digital computer system; means for converting an analog signal into a digital value when supplied with an analog signal address, said means connecting said plurality of analog signal sources to said digital computer system; a plurality of machine readable definitions each defining an analog signal scanning operation, and each specifying an analog signal address and a variable scanning frequency or period; means for operating said computer system to accept and to store said definitions; means for operating said computer system to establish linkages between groups at least portions of said stored definitions such that each group includes portions of definitions which specify the same scanning frequency or period; and means for operating said computer system to process each group of linked definition portions periodically at a rate determined by the scanning frequencies or periods specified by the definitions whose portions comprise each linked group, where processing comprises following the linkages from one definition to the next and carrying out the analog signal scanning operation called for by each definition. 2. A data gathering system in accordance with claim 1 wherein each definition is accompanied into the system by a designator which serves as a variable name, and wherein the system includes means for operating said computer system to establish a directory of designators each of which designators is stored within the directory together with the computer system address of at least a portion of the corresponding variable definition.