Lock input

2.7.2.2 PREEMPT CONTROL PARAMETER (bit 0) - The Lock Input parameter enables call 'memory' for the associated preempt input. If set to ON, any call that becomes inactive before the controller has completed timing the minimum dwell and minimum duration times will be retained. If the call becomes inactive during the delay time, it is also retained. Once these minimum times have been met, the call is treated normally; that is, it reflects the state of the preempt input. If this parameter is OFF, the call reflects the state of the preempt input. If the call ends before the delay time has elapsed, the preempt sequence does not occur.

The value is stored in the controller database for this object complies with the NTCIP definition Non-Locking Memory.  Lock Input set to ON is equivalent to Non-Locking Memory set to 0 (false).

Override Auto Flash

2.7.2.2 PREEMPT CONTROL PARAMETER (bit 1) - Setting this parameter to ON causes preempt calls to override automatic flash if it is in effect when the preempt call is received. The controller will return to automatic flash  at the end of the preemption.

If Override Auto Flash is set to OFF, the preempt does not override automatic flash if active when the preempt call is received. The preempt call is ignored as long as auto flash is active.

Override higher # preempt

2.7.2.2 PREEMPT CONTROL PARAMETER (bit 2) - (called Preempt Override preemptNumber +1 in NTCIP 1202).

NEMA defines the priority for preemption in numerical order (preempt 1 is the highest priority and preempt 10 is the lowest).  Override Higher # Preempt is typically used to alter the priority for preempts 3-6 (emergency vehicles) so that they can be serviced on a first come basis.

If Override Higher # Preempt is set to ON, the preempt has priority over higher numbered preempts.  If this parameter is set to OFF, then this preempt cannot interrupt higher numbered ones. Note that higher numbered preempts cannot interrupt lower numbered ones regardless of the value of this setting.

Flash in dwell

2.7.2.2 PREEMPT CONTROL PARAMETER (bit 3) - Flash in Dwell allows the controller flash indications during preempt dwell instead of dwelling in green.

If  Flash in Dwell is ON, phases in the Dwell Vehicle Phase list and overlaps in the Dwell Overlap list flash yellow during preempt dwell.

Link to preempt

2.7.2.3 PREEMPT LINK PARAMETER - The Link to Preempt parameter allows the current preemption to initiate a higher priority preempt. At the termination of the dwell time, the linked preempt automatically receives a call, which is maintained as long as the demand for this, the original, preempt is active. Linking provides a method of implementing dual track clearance intervals and other complex preemption sequences.