Trailer communications system

A tag unit for location on a trailer, the tag unit operating in either an inactive mode or an active mode, the tag unit comprising:

• a memory operable to store information relating to the trailer;
• an activating event detector operable to detect an activating event which occurs substantially simultaneously at the trailer and a remote location;
• a processor coupled to the memory and the activating event detector, the processor operable to transition the tag unit from inactive mode to active mode in response to the detection of an activating event;
• and
• a transmitter coupled to the processor, the transmitter operable to transmit the information stored in the memory during a window for communication established in response to the detection of the activating event by the activating event detector, wherein the information communicated between the tag unit and the remote location outside the window is considered invalid.

A method for communicating with a trailer comprising:

• detecting a predetermined event which occurs substantially simultaneously at both the trailer and a remote location;
• specifying a window for communication between a tag unit on the trailer and a reader unit at the remote location in response to the detection of the predetermined event;
• and
• communicating information from the tag unit to the reader unit, wherein information communicated between the tag unit and the reader unit outside the window is considered invalid.