TWCProtocolMonitor

Tesla Wall Connector Gen 2 Protocol Monitor

David Annett (david@annett.co.nz)

This is a program to snoop on the RS-485 communications between a Tesla Wall Connector (TWC) Gen 2 master and slave(s). It will decode the messages in to a human readable format.

The program takes a single argument, the serial port device name.

NB: This program has only be tested on Linux but other OSes should work fine.

Example output

For example here is a master sending a heartbeat message to a slave and the slave sending back a heartbeat reply:

16:34:14.321 (+0.401) Message 14
Ignored: (FC)
Response:    FB E0 79 73 34 95 00 00 00 00 00 00 00 00 00 95
  Command:   FBE0   PRIMARY_HEARTBEAT
  SRC TWCID:  7973
  DST TWCID:  3495
    State:           00 No current limit
    Max current:     0.00A
    Plug inserted:   00

16:34:14.522 (+0.201) Message 15
Ignored: (FC)
Response:    FD E0 34 95 79 73 00 00 00 00 00 00 00 00 00 95
  Command:   FDE0   SECONDARY_HEARTBEAT
  SRC TWCID:  3495
  DST TWCID:  7973
    State:           00 No current limit
    Max current:     0.00A
    Actual current:  0.00A

• The first line gives the local time, down to milliseconds, the lapsed time since the prior message and an incrementing message count.
• The second line show any characters send outside if the message packet frame. NB: One characters is actually needed, see Protocol.md for why.
• The third line shows the raw message, after the SLIP encapsulation has been removed, but including the checksum.
• The forth line show the message type.
• The fifth line shows the ID number of the sender.
• The subsequent lines depend on the message type.

Further reading

• Protocol.md gives a definition of the TWC Gen 2 protocol based on the limited public information available. It includes links to the information sources used.
• Real_TWC_Comms.md gives a break down of the message exchanged between real a TWC master and slave and notes on how the protocol is used. The related captures are in txt files include in this repo.

To do

This program is complete enough to be useful as is. Remain to do, but not a priority, are:

• VIN numbers are not decoded.
• Tag related to message length is misleading, probably should just show length.