The D400 EX (explosion proof) unit is completely contained in a rugged die-cast aluminum housing. The unit has a unique cover arrangement that allows for simple entry into the calibration/configuration chamber, while not exposing internal components and thus breaking the hazardous area classification. In order to reach the push button chamber, remove the two top screws on the face of the positioner. The lid will then open and 4 push buttons will then be available. The D400 can be fully calibrated and even configured from onboard push buttons.
After cover is opened, follow normal digital calibration procedures.