BMS Details

[lorenfb]

In the context of the CAN interface, what do you mean by an interface multiplexer?

There is nothing special about the Consult III+ hardware.

It is the Consult III+ software that has all the smarts (knows the requests and response formats).

Great reverse engineering effort on your part!

"In the context of the CAN interface, what do you mean by an interface multiplexer?"

Having the ability to off-load a PC's software from generating all the interface protocol necessary like
when using the ELM327. Typically a PC via a USB/serial port just sends basic commands to a hardware
interface multiplexer to generate the lower level protocols necessary to interact with various modules
on the multiple CAN buses. Such a device is typically called a "pass-through device". An example of
such a device is the SAE J2534 produced by a number of manufacturers.

Utilizing a J2534 device one can, for daily/monthly/annual fee, download an OEM's, e.g. BMW/Porsche,
diagnostic application and have access to a vehicle's modules for either diagnostics or reflashing.
Basically all OEMs are now required to provide an application to interface to the J2534 standard,
which runs on a PC and interfaces with a generic interface (a J2534 device). At the present most
OEMs just provide an application to only access their ECMs which may require field reflashing because
of emissions and/or running problems for their ICE vehicles

Nissan, as many OEMs have, provides a on-line application to access their ICE ECMs and a few other modules.
Obviously since the LEAF is a ZEV, Nissan doesn't need to provide any application to access the Leaf's
modules.

Having observed Nissan Leaf techs when doing a Leaf update, they use a Panasonic Toughbook
with an interface cable/module with an OBDII connector. Most likely their app runs under WinXp,
like most OEMs, and relies on the interface cable/module to function similar to a J2534. Not having
access to the Consult III+, I'm assuming that it would be setup very similar to my diagnostics systems
I use for BMW, Porsches, & M/Bs.

[Turbo3]

Sorry, I still have no idea what you are asking for.

J2534 has nothing to do with an electric vehicle. The Consult III+ hardware is not much different than an ELM. It receives frames to send on to the Leaf CAN and returns frames back to the attached computer.

There is no higher level function that is off loaded or an API. The only interface protocol is that needed to send/receive standard CAN frames. You give it an ID and up to 8 bytes of data and get an ID and up to 8 bytes of data back. That's all there is. The ID selects the ECU and the data contains the command and any modifiers. If you want to sound the horn just send the right command to the Body Control ECU.

So there is no such thing as an interface multiplexer for the Leaf unless you are calling what the ELM does an interface multiplexer. To the Leaf the Consult III+ just looks like another ECU that can send and receive CAN frames. The only difference is that the Leaf ECUs do not send data to the Consult III+ unless the Consult III+ has asked for it. The Consult III+ seems to make no attempt to capture any of the normal traffic on the CAN bus. It is only attached to the CAR-CAN so could not monitor any traffic on the EV-CAN even if it wanted to.

ICE have government mandated functions that must be implement. The Leaf being electric does not. They are very different. The Leaf CAN is a closed system only intended for access by Nissan service through the Consult III+. It is not an open spec. It is a proprietary interface know only to Nissan. Nissan does provide an interface box under NDA to interface to the Leaf which does isolate the CAN and provides a higher level interface but it provides a very limited set of information.

[JeremyW]

The Consult III+ seems to make no attempt to capture any of the normal traffic on the CAN bus. It is only attached to the CAR-CAN so could not monitor any traffic on the EV-CAN even if it wanted to.

Hmm, that's news to me. I don't think I've seen that mentioned before on MNL. Interesting.

Also, to be fair, ALL current EV's are proprietary with respect to CAN messages and such. It's not just the leaf.

[TonyWilliams]

Awesome work. What is the CAN message that is the "PWR" signal ?

[lorenfb]

1. Turbo3 asked:

"In the context of the CAN interface, what do you mean by an interface multiplexer?"

I answered:

"Having the ability to off-load a PC's software from generating all the interface protocol necessary like
when using the ELM327. Typically a PC via a USB/serial port just sends basic commands to a hardware
interface multiplexer to generate the lower level protocols necessary to interact with various modules
on the multiple CAN buses. Such a device is typically called a "pass-through device". An example of
such a device is the SAE J2534 produced by a number of manufacturers."

2. Turbo3 stated:

"Sorry, I still have no idea what you are asking for. J2534 has nothing to do with an electric vehicle. "

I didn't state nor implied that J2534 was intended for use with an electric vehicle, only that it exemplifies an interface multiplexer.

3. Turbo3 stated:

"The only interface protocol is that needed to send/receive standard CAN frames. You give it an ID
and up to 8 bytes of data and get an ID and up to 8 bytes of data back."

That's a very very limited functionality and is what the LeafSpy does, but really can't be considered
on the same level of an OEM diagnostic tool like the Consult III+, or what BMW/Porsche provides to
their service techs.

4. Turbo3 stated:

"The Consult III+ seems to make no attempt to capture any of the normal traffic on the CAN bus.
It is only attached to the CAR-CAN so could not monitor any traffic on the EV-CAN even if it wanted to."

That statement is rather confusing in that it implies that the Consult III+ is totally useless. In fact,
it has the same functionality/utility as any propriety automotive field diagnostic tool provided by any
ICE OEM with the exception that it's for the Leaf. The Consult III+ should have and has the capability to
access any module on any CAN to; read/erase fault codes, recode functionalities, e.g. when doors auto
lock, or when a replacement module is installed, read actual module sensor data, e.g. ABS wheel speeds,
and reflash modules when a major module update is required. Without that functionality, Nissan dealers
could not adequately field support their vehicles.

5. Turbo3 stated:

"ICE have government mandated functions that must be implement. The Leaf being electric does not. They are very different."

Most are aware of this!

My post:

"Nissan, as many OEMs have, provides a on-line application to access their ICE ECMs and a few
other modules. Obviously since the LEAF is a ZEV, Nissan doesn't need to provide any application to
access the Leaf's modules."

6. Turbo3 stated:

"The Leaf CAN is a closed system only intended for access by Nissan service through the Consult III+.
It is not an open spec. It is a proprietary interface know only to Nissan. Nissan does provide an
interface box under NDA to interface to the Leaf which does isolate the CAN and provides a higher
level interface but it provides a very limited set of information."

1. All OEM vehicle CAN systems, whether ICE or not, are proprietary systems ("closed systems"),
with the exception of OBDII and ECMs.
2. So Nissan does utilize an interface box (a multiplexer).

Hardly any great insight provided.

[TomT]

You know, if you EVER want people to actually take you seriously and/or provide any help to you, you MIGHT want to try being a little nicer and less snarky...

Hardly any great insight provided.

[Turbo3]

lorenfb,

This has gotten way off topic for this thread.

You should start a new thread under Leaf Ownership/Accessories/Mods >>CANBus if you would like to continue to discuss this. Once you do that I will move my comments over to it and clear them from here. Please do the same to clean up this thread.

Only BMS comments should be posted here, Thanks.

Jim

[Turbo3]

Awesome work. What is the CAN message that is the "PWR" signal ?

The "PWR" signal comes from a relay that closes when you press the Power Button. If you look closely by the ELM adapter there is a small switch to 12 volts that I use to generate this signal.

[Turbo3]

Can you do a log of the can "bus" with just the BMS on it to see what messages show up? Should confirm which messages we know are from the BMS and learn any that we don't know.

I see the following message IDs on the EV-CAN coming from the BMS board.

0x1db, 0x1dc, 0x55b, 0x59e, 0x5bc, 0x5c0

[Turbo3]

Updated the first post with a third (page 2) schematic showing the isolation between the two groups of 12 ASICs.

Added a "Notes" section to the first schematic.

Here is a sample trace of the serial link running at 19,200 baud. The processor sends an address followed by a string of pulses used by the addressed ASIC to send data back (lower trace).



Because only 2 ASICs are powered up the processor spends most of its time in retry (2 seconds per ASIC). So a full trace takes over 40 seconds to capture.

The data captured in the above trace should be the voltages for the 4 "cells" it thinks are attached. Actually it must be the voltages as that is the only data coming back to the processor from the powered ASIC.