The 651CD2S1N Digital/Analog Pressure Controller features a 0.5 amp power supply and drives MKS 653 or 253 Exhaust Throttle Valves with speed and precision. Its self-tuning algorithm brings the system to set point faster than conventional controllers, and ensures repeatable process recipes without operator involvement. The self-tuning function determines optimal control parameters for any set point in the range of the valve by learning time constants, transfer functions of the valve and plumbing, valve gain, and other important parameters. The 651 includes adjustable soft-start functions for each set point, as well as open and close functions to minimize turbulence in the chamber; local/remote transducer zeroing capability; and two relays to activate other system functions, or to indicate if the pressure deviates from the desired set point. All controls are easily accessed via a simple-to-use front panel, or remotely through RS-232, TTL, or analog voltage. An LCD readout shows valve position and displays pressure in a wide range of engineering units. Five preprogrammable set points are provided for pressure or position control.