Abstract: A process control system for monitoring and controlling elements of a process. A control unit is electrically connected to a multi-conductor cable upon which are removably connected in series configuration a plurality of serially addressable control modules. The control modules are removably connected to elements of the controlled process to permit monitoring and control of the elements. The modules may be readily connected to or removed from the process elements and multi-conductor cable, to permit expansion or modification of the control system as needed for proper use in controlling process systems. The control modules operate independently from outside signals in monitoring the process elements, and respond to selected element status conditions by accessing communication with the central controller on a priority basis over other control modules in the system. The control unit includes a touch sensitive video screen for providing information to an receiving instructions from a user.