The GPS Log Book device makes intelligent decisions when your vehicle moves to determine when you are in a trip (moving) and when you are stationary).  If your vehicle is stationary for 5 minutes (by default) the device stops recording and records the trip up to when your vehicle actually stopped. 

This setting can be adjusted on request if required.  You could extend this period for up to 15 minutes, or have the device record trips whenever it is powered, although this can easily cause all of your trips to merge into one single, very long trip!