CAN Bus speed on the 2004 Boxster?

[PorscheFan5]

For my conversion I am thinking of using a Orion BMS and an EVIC display. Both of these work of off the CAN Bus. That means I can connect (to) the vehicle's CAN Bus also. However all the CAN Buses need to be operating at the same speed.

The CAN Bus speed for both the Orion BMS and EVIC display, as expected, can be modified/configured. I would assume it is not possible/easy to modify the vehicle's CAN Bus speed. Therefore I will have to adjust the CAN Bus speeds of both these devices to the speed of the vehicle's CAN Bus.

Does anyone know 'what is the CAN Bus Speed of the 2004 Boxster Base model, or where I can find this info?

Thanks in advance for your help on this!

[PorscheFan5]

No one?

Does the Durametric SW show the CAN speed by any chance? I am guessing not, but checking...

Appreciate response from the experts on the forum...

Thanks for your help in advance.

[Bayley]

Which CAN bus, chassis or powertrain?

If you're going to the EVIC, I would assume it's on an interior / chassis bus. The 83.333K fault tolerant bus was standard fair for Daimler and VW in the early 2000s but I don't recall what Porsche was using back in those days. They might have been using a 125K. Either way, it's also a fair assumption that the network was using standard 11 bit message IDs.

As far as powertrain, 500K is a pretty safe bet.

If you need to know for sure before hooking anything up, GridConnect.com sells a CAN bus to USB adapter for $399. Unless you have a friend with a Vector CAN Case setup they can let you use for free, this is the least expensive way to sniff the CAN bus.

[Qmulus]

FWIW, there are a few different reasonably priced CAN interfaces out there. I have a Kvaser Leaf Light HS that seems to do what I need, and came with some good software tools. That setup was recommended to me by a guy from Bosch Motorsport for a project I am working on. I know people also use Value CAN and some others. As Bayley mentioned, the industry standard tools that the manufacturers use is made by Vector

The reason we are mentioning the CAN tools is that the speed is going to be easy to figure out once you sniff the bus. You WILL need to get the CAN message sorted out on a working system with the engine, ABS, and cluster all working before you pull it out. That is not a trivial job and as far as I have found, you will not just find documentation for the Porsche CAN communication.

I guess the big question is, what are you trying to accomplish?

[PorscheFan5]

Bayley and Qmulus,

"Which CAN Bus - engine, drivetrain?...What are you trying to acheive?" Great questions. Let me see if I can clarify.

• I am working on converting my 2004 Boxster to EV
• Engine is out and won't be going in...:-)
• All components related to engine - cooling etc. will not be needed - so coolant lines and radiator are out
• Am using the stock clutch, FW and 5 spd Tx
• Am using a Orion Battery Management system that supports the CAN Bus
• Will be connecting an Andromeda display to the Orion BMS and my Elcon charger (if possibe) through CAN Bus supported on BMS
• As of now an thinking that I will leave the DME alone and just keep it there connected with whatever components are left
• Have been told that most of the other components (other than engine) work quite independently so even if engine is not present the DME will not pose a problem. Yet to be proved right/wrong...
• My thought is most of the DME output signals are either going to the engine or are controlling the engine. So since no engine, no use of the control signals (or pick up signals).
• Am having the hole slotted for the stock hall effect sensor in the EV adapter plate. Will see if I was to wire the original RPM sensor the RPM shows up on the stock RPM meter in dash...Yet to be seen...not sure what challenges that will pose
• Am thinking of connecting the vehicle's CAN bus to the CAN Bus of the Orion BMS and Display in hopes that I could also show RPM that way and other info on the CAN Bus
• IN order to connect the two CAN bus' I need to have them running at the same speed.

Hence the questions...Hope that helps. Please poke holes in the above so I know what may work and what won't.

Regards.

[Qmulus]

I see no reason to keep the stock DME, nor connect to the powertrain CAN bus for that matter. What information do you think you need to transfer from one system to the other? The messages that the DME would generate just aren't applicable to the electric motor, other than the RPM. My guess is that the display you are talking about already has the motor RPM. The DME calculates RPM via the flywheel 60-2 tooth pattern, so at a minimum you will need to keep the flywheel and sensor and connect it to the DME.

Considering that you no longer have a working drive train, the only way to get the CAN message information (IMO) is to sniff a working/running vehicle to see what exactly is needed. There really is no other way, unless you find someone who has done it and will give you the information. Companies like MOTEC and AIM have that information for their race displays, but they don't make it public. You will no find a Porsche spec that just lists the message structure and required messages. It would be a big effort to reverse engineer it. BTTT. Years ago I helped a company that was trying to do a similar conversion using a new Mercedes SL. They stripped out the drive train, and installed the electric motor, controller, etc., THEN thought about integration. Whoops, too late. That should have been done BEFORE taking it all apart. I helped them start analyzing the CAN data from another similar car so they could program a separate module to keep the chassis happy without the engine and transmission controls. They hadn't budgeted for my services, so I wasn't there long. Just enough to get them going. I don't know if it ever got completed properly.

My guess is that your car wasn't running when you decided to convert to electric, so getting data from your car likely wasn't possible. The good news is that the Boxster is pretty simple. I honestly think that you can do without the CAN integration. Sure, you will have fault codes in the ABS and instrument cluster for no communication with the engine controls, but everything will work other than the tach and misc. oil pressure, temp and charge indicators that aren't applicable to your system. Might as well take the LEDs out for those. I would not leave the DME in just for that stuff. It might not be too difficult to figure out the engine RPM message and use the EV controller to put that on the powertrain CAN bus. My bet is that you won't bother...

[PorscheFan5]

Thanks for the suggestions Qmullus. You are corect in assuming that my engine was not running whe I started the project. In fact I bought the vehicle with a busted engine intentionally...unbeknownst to this need...

I am where I am. I would like to see if I can use the current DME 7.8 for:

• Not having to deal with ABS, Airbag etc lights
• Use the current RPM sensor and wiring to display RPM on the stock dial in the dash. And not put another sensor on DC motor shaft and have to put another meter somewhere to see RPM
• Any other info that I could get from the CAN bus that I can feed to my display using the analog or digital input connectors.

Could you spare a few minutes for a live conversation on the phone? I could get soe insights from your experience you mention. Worst case I will remove the DMW completely...Please PM me if you could spare me a few minutes.

Thanks!

[The Radium King]

my understanding is that the canbus system is dealing with mostly wheel speed info, so is connected to the abs system, the gauge cluster and the hvac system (ie, speed as it applies to driving the ac compressor). you can use pre-canbus components from a 2000/earlier car, but would have to convert to 3-channel abs. personally, I would keep the oem system in place and just install a parallel system where required - what's what most of the other engine conversions (ie ls, subi, audi) do.

[Qmulus]

Just because the engine control module is out of the system doesn't mean the rest of the components on the CAN bus won't work. Well, maybe if it needed to be terminated, but that is just a resistor to add. Everything is in parallel on the CAN bus, so removing one component won't bring it all down. The ABS will still work (although it will not be able to tell the motor to reduce torque, if this ABS system does that - do you have PSM?), whatever is left of the HVAC will work (although with no engine to create hot coolant or turn the AC compressor it can't do much...), the airbag system should be fine (just my opinion, don't blame me if it for some reason it doesn't). There will be fault codes because the different modules won't see expected messages, like the HVAC will want to see coolant temp, but does it matter if there is no coolant? I don't think so. No, you will not be able to use the existing drive by wire pedal without modification, unless by some chance the EV system you have uses potentiometers that are calibrated the exact same way. That is NOT a CAN thing, these are discrete analog signal wires to the DME.

I can understand that motor RPM would be good to know. Ideally you would have the electric motor control send the CAN RPM message in "Porsche" format. To figure out that message takes the reverse engineering. You may find other messages would be helpful as well, but that will only come once you dig into it. This is work you are will likely need to do yourself, as it is specialized and expensive. From experience I can say that unless you are fabulously wealthy (or fabulously eccentric) and this is just a toy you are making that has to be right, I highly doubt you would want to pay what someone would charge to figure this all out and program it up. I can also say that I have never seen anyone go to the expense or trouble to do it all "right". Generally, they get the motor in the car, start driving it, and that is it. The easiest and most straightforward (albeit ugly in my opinion) way to get motor RPM is to leave in the original engine control and wire a crank position sensor to read the motor RPM from the flywheel or some 60-2 wheel you put on the motor shaft. ANYTHING other than that is going to be a big job.

Perhaps there are folks in EV forums that have done all of this already and can help you more. Finding those people would be my suggestion. Maybe they even use the fuel gauge to display charge state and calibrate the OBC to give correct range. Hmmm...