RT_SB_INS_Vpt1_Offset: INS Virtual Point 1 Offset
RT_INS_Vpt1_Offset: 143, 0 (0x8F0020 + unit id) (0x3C0)
Bytes 0-1: Virtual point 1 offset X (+ve ahead)
Bytes 2-3: Virtual point 1 offset Y (+ve right)
Bytes 4-5: Virtual point 1 offset Z (+ve below)
Resolution of offsets is m / 1000.