RT_CFG_Update_End_Marker_1: Update end marker heading
RT_CFG_Update_End_Marker_1: 159, 19 (0x9F1320 + unit ID) (0x7D3)
Bytes 0-1: End Marker Heading
Bytes 2-7: Unused
Heading is unsigned, in the range 0..360 degrees.
Heading resolution is degrees/100