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Vishnu Technical: Teaser Datalog
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12-01-2009, 01:47 PM | #45 |
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It is impossible to modify a can bus message by overwriting it.
The boost data flowing on the bus (for example) are always sent by the engine ecu and must respect the BMW ranges. The modification of such signals is operated as on all the piggys by physically intercepting the wires originally cabled to the engine ecu and subtituting them with the Procede ones. The only messages on can bus that the Procede is able to influence without relevant drawbacks are the various activation commands (such as the code clearing) that are not frequently updated by other nodes on the network. |
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12-01-2009, 01:49 PM | #46 | |
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The canbus is a DIGITAL network containing the data of over 200 real-time parameters being pulled, calculated, and read by the DME, The PROcede is the ONLY piggyback, EVER, to listen or talk on the canbus network.... which allows the procede to modify its analog sensor signals based on this data, as well as talk directly on this digital network to get the car to do things like flash the SES light, or hit its exact boost targets. It takes piggyback tuning to a whole 'nother level... as you now have access to all the fun stuff that only a flash could do in the past, and then you have more contol than a flash, because you can actually deploy your own boost control logic by directly controlling the wastegates and other signals with the piggyback, allowing for an even greater level of control than any flash or piggyback has ever seen. That's how I understand it anyways -Rick |
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12-01-2009, 02:09 PM | #47 |
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12-01-2009, 02:11 PM | #48 |
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No, but it would be possible to intercept the message with one CAN transceiver and repeat a modified message out another.
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12-01-2009, 02:52 PM | #49 | |
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This is possible, but absurd for the kind of application because you had to replicate hundred of messages in order to change five of them (not to say the safety related issues and the unavoidable time delay induced). P.S. The engine is NOT using Can bus messages in order to work properly. It relies on the hardwired sensors only. The mesaages are communicated on the bus in order to share them with other subsystems and for debug. |
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12-01-2009, 02:58 PM | #50 | |
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That's what I was saying as well.
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12-01-2009, 03:02 PM | #51 | |
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The great potential of the canbus integration is on READING messages such as boos target and actual ignition advance. |
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12-01-2009, 03:13 PM | #52 |
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12-01-2009, 03:20 PM | #53 |
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quote: "The CAN bus is a broadcast type of bus. This means that all nodes can "hear" all transmissions. There is no way to send a message to just a specific node; all nodes will invariably pick up all traffic. The CAN hardware, however, provides local filtering so that each node may react only on the interesting messages" unquote.
So one can pick up a can message with another device (node) and replace that message with a different value. But by then the ECU will have received the original unmodified message already and must be throwing up fault if it sees the same message coming it at double frequency but with two different values? |
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12-01-2009, 03:27 PM | #54 |
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CAN messages are broadcast to all nodes on the bus, but messages are set up with 11 or 29 bit identifiers, and each device has filters set to "nab" the messages that pertain to it. At least, that's how it works in the industrial automation industry. We actually do CAN projects with Bosch on automotive components.
If you set up a device in-line from a source, and have it catch all identifiers, repeat those which its application layer determines don't need modification, and modify then resend the ones that do need modifying, then I can see how this would work; however, I'm unsure as to the effect, if any, of the delay or skewed timing of those messages. |
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12-01-2009, 04:21 PM | #56 |
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There is no speculation, only people correcting misinformation provided by your tuner. You can not modify sensor signals via CANbus. Only read existing signals. In addition the PROcede is wired to "tap" the CANbus signal not intercept/retransmit so even the imaginary solution of capturing and retransmitting is not plausible. I say imaginary because the signals originate in the ECU from hard-wired sensors and are transmitted out for other modules to reference. Not read by the ECU via CANbus as some have suggested.
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12-01-2009, 04:24 PM | #57 | |
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One of the few worth to discuss with here (about technical stuff at least) . |
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12-01-2009, 04:25 PM | #58 | |
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12-01-2009, 04:42 PM | #59 | |
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12-01-2009, 04:45 PM | #60 |
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Good information guys, at least this will help less technical people to understand what is actually going on here with this CAN bus.. Helped me to understand better this point.
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12-01-2009, 04:48 PM | #61 | |
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And anyone who has datalogged the flash, can attest to throttle closure events while driving. It's just interesting that so many people are of the opinion that flashes are immune to such issues when, in fact, they are more prone to it. Shiv |
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12-01-2009, 04:53 PM | #62 |
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CANBL for short? (like Campbell soup.......lol)
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12-01-2009, 04:59 PM | #63 | |
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12-01-2009, 05:05 PM | #64 | |
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Maybe the rollers inertia of the Maha is higher respect to the dynojets commonly used in USA. The test I'm speaking of lasts 15 seconds for a complete pull from 2000 rpm to redline. From your log I see a total time of about 9s: I imagine we are talking of a complete IV gear dyno test also in this case. If so, my assumption would be confirmed (together with GIAC claims) P.S. The boost build up on the first graph you posted (so the old boost logic) is still very similar to the GIAC one I received. Probably also faster considering the higher pressure level reached and the lower load due to the Dynojet. |
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12-02-2009, 02:06 AM | #65 | |
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12-02-2009, 08:19 AM | #66 | |
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