transponder-bridge.md

I found this online and it seems to have been copied and pasted from a bunch of sources so no idea who to credit.

For the I-Lap hardware there are two known response packets To start the lap counter you must send the following command:
01 25 0D 0A

This initializes the lap counter into 7 digit mode This will respond with a packet that looks like the following:
01 25 09 32 30 34 09 30 09 30 0D 0A

The breakdown is the following:

• Byte 1 is the header, 01
• Byte 2 is the packet type, 25 (%) for an initialization packet
• Byte 3 is a seperator character, 09 seperates fields
• Bytes 4-6 are the decoder id in ascii, 204 in this case
• Byte 7 is a seperator, 09
• Byte 8 is not used set to 0 in ascii
• Byte 9 is a seperator, 09
• Byte 10 is not used set to 0 in ascii
• Bytes 11 and 12 are the ending delimiter, 0D 0A is a new line character sequence

After the lap counter is initialized it will send a packet each time a car is detected. An example packet would look like this:
01 40 09 32 30 34 09 33 34 35 36 37 38 39 09 33 32 34 2E 36 32 30 0D 0A

The breakdown is the following:

• Byte 1 is the header, 01
• Byte 2 is the packet type, 40 (@) for a transponder packet
• Byte 3 is a seperator character, 09 seperates fields
• Bytes 4-6 are the decoder id in ascii, 204 (32 30 34) in this case
• Byte 7 is a seperator character, 09
• Bytes 8-14 are the transponder id in ascii characters, 3456789 (33 34 35 36 37 38 39)
• Byte 15 is a seperator character, 09
• Bytes 16 - 22 are the time, it starts counting up when initalized, this field can vary in size, time is in the format SECS.MSS, 324.620 in this case
• Bytes 23 and 24 are the ending delimiter, 0D 0A is a new line character

A second example would look like this:
01 40 09 32 30 34 09 33 31 37 34 39 36 36 09 31 32 2E 32 32 36 0D 0A

This has a transponder 3174966 and a time of 12.226

Third example:
01 40 09 32 30 34 09 37 32 35 31 33 31 38 09 34 2E 34 34 38 0D 0A

This has transponder 7251318 and a time of 4.448