Abstract: A system for monitoring and control of an industrial installation, such as a chemical plant, having a large number of operating parameters which have to be maintained between well defined limits which may be fixed or may vary in time in a predetermined manner, comprising a plurality of sensors, one for each parameter being monitored, four digital computers arranged in matrix configuration, two of them having peripheral memories as well as central memories, and means for converting the essentially analogue signals from the sensors into encoded, serialized digital signals for the computers each of which has an associated watch dog detector which senses if it should go faulty and in such event instructs the other three computers or one of the other three computers to take over its functions.

Abstract: In a computer-controlled mercury cell plant comprising a cell room, a mercury cell in the cell room, a control room remote from the cell room, and a central control apparatus including a memorized program digital computer arranged to adjust the height of anode banks in the cell in response to analog signals supplied by anode current sensors associated with the banks, a substation is provided in the cell room by means of which the analog signals are multiplexed, digitalized, encoded and serialized before leaving the cell room and are sent to the central control apparatus through a telephonic loop. The substation is preferably situated adjacent a front end of the cell at a distance not exceeding 2 meters. Signal disturbances and use of bundles of cables are thus avoided.