Distributed environmental process control system

Abstract

A process control system includes a high speed serial backbone communications network, interconnecting a plurality of microprocessor based nodes that each act as the master to a high speed serial branch network comprising device controllers, such as air flow valve controllers and transducers. The primary network may operate in a time division multiplex mode whereby a node acting as a synchronizing station periodically issues a synchronizing signal that commands each node to execute a branch network control sequence, during which each node gathers and operates upon data it collects from the device controllers within its branch network, and issues commands based thereon to the branch network. An ensuing communications sequence also triggered by the synchronizing signal enables each node on the primary network to transmit a command or a response to any other node and, through such other node, to any device controller in any branch network of the system. Serial ports on each node permit user access from any node on the primary network to any other point on the system for purposes of monitoring and control. Serial ports on each device controller permit user access to local device parameters.