This is a version of the Hiway Cable Interface for the High Level PIU, used when Sequence of Events is implemented across multiple PIUs.

This card is identical to the standard cable interface, PXDH11, except for the addition of a precision crystal oscillator. This precision oscillator insures one millisecond resolution when the system includes SOE on multiple PIUs.

Without the precision oscillator of the PXDH12, the standard oscillator of the PXDH11 provides SOE resolution of 2 milliseconds between points on different PIUs.