Serial (RS232) Protocol

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:  

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.

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.
 

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

(-1)^s x 2^e-127 x (1.f)₂

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

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;