Mobile TacSIM is a PC based portable tactical communications, data link and radar simulation system that uses ruggedized, commercial off-the-shelf hardware configurations for enhanced reliability and durability. Mobile TacSIM functions much like an actual Tactical Data System (TDS) except that the Simulation Object Database from which messages are generated is initiated through manual operator actions, scenario events, and/or simulation data link input (e.g. DIS) rather than from sensor inputs. External interfaces configured into the TacSIM independently scan the Simulation Object Database and generate the appropriate primary and amplifying messages for each object. Message generation is based on the visibility of the object (e.g. radar coverage area), availability of data, and requirements of the associated specification (e.g. MIL-STD-6016F). Data received over a configured external interface is validated for errors and processed for automatic link responses (R2 shifts, ID conflict processing, command processing, etc.), presentation of new data in hook readouts, real-time data reduction, and automatic alerts. Non-periodic message traffic such as Data Update Requests, ID Differences, etc. are generated in response to operator actions (and scenario events) as well as in response to received messages.