[Ovmsdev] TEMPS screen - CAN bus analysis required

[Mark Webb-Johnson]

A question on tmc reminded me we need to look into this. Anyone out there with a can bus analyzer and some time?


It appears (we can only guess from looking at CAN bus messages) that the VDS tells the VMS what it is interested in, and from that point on the VMS broadcasts the interested messages on the can bus. So, calling up the temperature screen on the VDS makes the VMS start transmitting temperature messages. If you never call up that screen, the messages are never sent. You fixed it yourself ;-)

How long does the VMS keep sending? Indefinitely, from what I can tell. there must be some 'deep sleep' event that would cause it to stop, but mine is certainly being sent and it has been months since I called up that screen.

It would be nice to be able to 'spoof' that message to say the VDS is looking at the temperature screen, but so far we don't have enough information on those messages to know for sure what they mean. [I]I really don't like transmitting messages on the can bus if we don't know with 100% certainty what they do.[/I] If anyone wants to help out with this analysis, please do. The messages appear to be on can id 0x102, B1=0x06. Here is some data I've captured (from canbus_notes.txt):

                      Samples:
                         0.4166 102 06 10 27 00 10 00 00 00    VDS-> (message from VDS 06)
                         5.9171 102 06 10 27 00 10 00 00 00    VDS-> (message from VDS 06)
                        11.4773 102 06 10 27 00 10 00 00 00    VDS-> (message from VDS 06)
                        17.0587 102 06 10 27 00 10 00 00 00    VDS-> (message from VDS 06)
                        22.5380 102 06 10 27 00 10 00 00 00    VDS-> (message from VDS 06)

                        On switch to TRIP screen:
                                102,06,10,27,00,00,09,10,00
                                102,06,D0,07,00,00,01,80,00
                        On switch to TEMP screen:
                                102,06,10,27,00,00,01,80,00
                                102,06,2C,01,00,00,09,10,00
                        On switch to BATTERY screen
                                102,06,10,27,00,00,09,10,00
                                102,06,E8,03,00,00,01,00,00
                        On switch to GRAPH energy use screen
                                102,06,10,27,00,00,01,00,00
                                102,06,64,00,00,40,00,00,00

                        Investigating:
                        Car seems to suppress the id#100 B1=A3 temperature message until the TEMP screen is brought up.
                        Tried to send the 102,06,D0,07,00,00,01,80,00 message, and that appeared to start id#100 B1=A3 temperature message transmission.

Reproducing this is easy. Get a car that is _not_ sending temperature messages (id 0x100 B1=0xA3). Call up the temperature screen on the vds and magically see the temperature messages start to appear on the can bus. Now, work out which can bus message sent from the VDS (id 0x102) caused those temperatures to start to be sent. Also, work out which can bus message can stop them...

If we could find the 'stop sending temperature readings' message, then testing the 'start sending temperature readings' message would be easier ;-)

Regards, Mark.

http://www.teslamotorsclub.com/showthread.php/6655-Open-Vehicle-Monitoring-System?p=131846&viewfull=1#post131846



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