The Calibration Solenoid Valve (BO) option creates an output to interface to one or more Calibration Solenoid Valves. This selection is always available. Select this option to use calibration solenoid valves during the autocalibration process for spaces that must remain in control at all times (for example, labs or hospital rooms with supply exhaust boxes). All damper outputs stay at their current value during this 10 second process. The BO is connected to the State Selector through the Calibration Solenoid Pass Through module. The BO zeroes the differential pressure for the Differential Pressure sensor during autocalibration. The effective stroke time for the autocalibration sequence module changes to 10 seconds when this option is selected to speed up the process. Use this BO for all Differential Pressure sensors in the system (Exhaust Box).