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RACELOGIC Support Centre

VBOX 3i Serial (RS232) Protocol

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VB3i Serial String Format

115200 Baud, no parity, 8 data bits, 1 stop bit

Message format: 

$VBOX3i,nnnn0000,stttaaaaoooovvhheeezzyyxxffffjjjj1111222233334444lpddddddqqrrii77778888kkmmmgggg559966cc

The $VBOX3i and commas are in ASCII, the rest is in binary.
 

Although not all of the channels listed below are present in the serial stream unless selected in VBOX Setup software, the table shows the order in which they appear in the data stream

Enter first 4 bytes (nnnn) as 8 characters of hexadecimal:  

 

  Format Bytes Description nnnn, bit mask.
nnnn   4 Reserved to indicate channel presence  
0000   4 Reserved  
s Integer 1

Satellites

Number of satellites

0x00000001
ttt Integer 3

Time

Number of 10 ms ticks since midnight UTC

0x00000002
aaaa Signed 4

Latitude

(MMMM.MMMMM * 100,000)

Signed Integer of Decimal minutes *100,000.

Positive = North, Negative = South

0x00000004
oooo Signed 4

Longitude

(MMMMM.MMMMM * 100,000)

Signed Integer of Decimal minutes *100,000.

Positive = West, Negative = East

0x00000008
vv Integer 2

Velocity

Velocity in Knots * 100

0x00000010
hh Integer 2

Heading

Degrees from true north * 100

0x00000020
eee Integer 3

Height

Altitude. In metres WGS84 * 100

True signed 24 bit number

0x00000040
zz Signed 2

Vertical Velocity

Vertical velocity in m/s * 100

0x00000080
yy Signed 2

Lat acc (GPS)

Lateral acceleration in g * 100

0x00000100
xx Signed 2

Long acc (GPS)

Longitudinal acceleration in g * 100

0x00000200
ffff Integer 4

Brake Distance

(m *12800)

0x00000400
jjjj Integer 4

Distance

(m *12800)

0x00000800
1111 Float 4 Internal analogue ch1 0x00001000
2222 Float 4 Internal analogue ch2 0x00002000
3333 Float 4 Internal analogue ch3 0x00004000
4444 Float 4 Internal analogue ch4 0x00008000
l Integer 1

GLONASS satellites

Number of GLONASS satellites

0x00010000
p Integer 1

GPS satellites

Number of GPS satellites

0x00020000
dd   2 Reserved 0x00040000
dd   2 Reserved 0x00080000
dd   2 Reserved 0x00100000
qq Integer 2 VBOX Serial Number 0x00200000
rr Integer 2 Kalman Filter Status 0x00400000
ii Integer 2 Solution Type 0x00800000
7777 Integer 4

Velocity Quality

km/h * 100

0x01000000
8888 Signed 4 Internal Temperature 0x02000000
kk Integer 2 CF Buffer size 0x04000000
mmm Integer 3

RAM Address

Free space on CF *980991 = Full, 0 = Empty

0x08000000
gggg Float 4 Event time 1 0x10000000
55 Float 2 Event time 2 0x20000000
99 Integer 2 Battery 1 Voltage 0x40000000
66 Integer 2 Battery 2 Voltage 0x80000000
cc   2 Checksum
CRC of message, See Note 1*
 

Note: ffff - Brake Distance: After the initial trigger activation, any new trigger activations within 2 seconds are ignored. After 2 seconds, if speed >2.7 km/h, new trigger input will reset the Brake Distance counter.

NEWCAN Serial String Format

When CAN channels are also selected to be present in the Serial data stream the data stream will look like the following:

$VBOX3i,nnnn0000,stttaaaaoooovvhheeezzmmmggggcc$NEWCAN,####,1111.....WWWWXX

 

$NEWCAN,####,1111.....WWWWXX  is the additional CAN channel information to the serial data stream.

The XX is a two byte checksum. - This is the same format as before see NOTE 1 below

The format for the serial string is $NEWCAN,####,1111.....WWWWXX

Where #### is a 32-bit value, representing the number of bytes to follow.
 

The order in which the data will come across depends upon the order in which you select the channels from the set-up screen. For example if the first channel you choose to log is FIM Channel 1 then the first 4 bytes will contain the data from the FIM. If the second channel was ADC02 Channel4 then the next 4 bytes will contain data for the ADC02. If you then remove (choose not to log) FIM Channel 1 and select ADC02 Channel 1 then the first 4 bytes will now contain the data for ADC02 Channel 1.
 

The data transmitted for each channel is in a standard IEEE 32 bit Float  format.
 

  Bytes Description Bit mask
ffff 4 CAN channel 15 0x7FFF
$NEWCAN 7 String header  
#### 4 Reserved to indicate channel presence  
, 1 comma separator  
1111 4 CAN channel 1 0x1
2222 4 CAN channel 2 0x3
3333 4 CAN channel 3 0x7
4444 4 CAN channel 4 0xF
5555 4 CAN channel 5 0x1F
6666 4 CAN channel 6 0x3F
7777 4 CAN channel 7 0x7F
8888 4 CAN channel 8 0xFF
9999 4 CAN channel 9 0x1FF
aaaa 4 CAN channel 10 0x3FF
bbbb 4 CAN channel 11 0x7FF
cccc 4 CAN channel 12 0xFFF
dddd 4 CAN channel 13 0x1FFF
eeee 4 CAN channel 14 0x3FFF
, 1 comma separator  
gggg 4 CAN channel 16 0xFFFF
hhhh 4 CAN channel 17 0x1FFFF
iiii 4 CAN channel 18 0x3FFFF
jjjj 4 CAN channel 19 0x7FFFF
kkkk 4 CAN channel 20 0xFFFFF
llll 4 CAN channel 21 0x1FFFFF
mmmm 4 CAN channel 22 0x3FFFFF
nnnn 4 CAN channel 23 0x7FFFFF
oooo 4 CAN channel 24 0xFFFFFF
pppp 4 CAN channel 25 0x1FFFFFF
qqqq 4 CAN channel 26 0x3FFFFFF
rrrr 4 CAN channel 27 0x7FFFFFF
ssss 4 CAN channel 28 0xFFFFFFF
tttt 4 CAN channel 29 0x1FFFFFFF
uuuu 4 CAN channel 30 0x3FFFFFFF
vvvv 4 CAN channel 31 0x7FFFFFFF
wwww 4 CAN channel 32 0xFFFFFFFF
ZZ 2 Checksum  

32 bit Float numbers

The bit pattern b1b2b3...b9b10b11...b32  of a word in a 32-bit machine represents the real number
 

(-1)s x 2e-127 x (1.f)2

where s = b1,  e = (b2...b9)2, and f = b10b11...b32.  
 

VB3i11.png
 

Note that only the fraction from the normalized mantissa is stored and so there is a hidden bit and the mantissa is actually represented by 24 binary digits.

Example of the Fraction part of the calculation the 23 bits 01110111100110110011110 would be come 1. 01110111100110110011110
 

The 23 bits after the 1. represent the presence of the binary weighted fractions ,½, ¼, 1/8, 1/16, 1/32,1/64 etc.

 

*Note 1

CRC Calculation example :

s[n] is a string containing the message

Polynomial:= 4129

CRC:=0;

for Loop:=1 to Length(s) do

begin

Temp:=s[Loop];

CRC:= CRC xor (integer(Temp) * 256);

CRC:= CRC mod 65536;

for i:=7 downto 0 do

begin

if ( (CRC and 32768)=32768) then

begin

CRC:= CRC *2 ;

CRC:= CRC xor Polynomial;

end

else

begin

CRC:= CRC *2 ;

end;

CRC:=CRC mod 65536;

end;

end;

result:=CRC; 

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