The VAC D400 is a microprocessor based, “intelligent” instrument that can be mounted to rotary or linear pneumatic actuators for accurate positioner and/or process control. This unit, while sophisticated in its accuracy and performance, is simple to mount, calibrate, and with good filtered air and proper maintenance, can provide very accurate and trouble-free service for many years. VAC D400 Digital Positioner Available with Hart, Foundation Fieldbus, or Profibus communication, the D400 range of applications and communications meets the latest industry standards. The “efficiencies” of the D400 are not only in its microprocessor based technology and accuracy, but also in the pneumatic air handling where air consumption is kept to a very minimum.