Desperate need of CAN-bus help

Hi,

I've been doing research on how to activate CAN on my ECU and I am overwhelmed with confusion. Any help I can get will be greatly appreciated.

I am delivering an engine with an onboard ECU (from Woodward) which is CAN-ready. There is an isolated port with 4 pins (CAN_H, CAN_L, Com, and Shld). I need to make various engine parameters (i.e. coolant temp. and oil pressure) available through CAN becauase the engine is being thrown into a system with various other components and a controller.

My main confusion is where the sensors are wired. These are standard analog/boolean automotive sensors. Do the sensors represent "Nodes" in a CAN system, or do the analog signals go to the ECU analog inputs and then passed through the ECU to the CAN port via software?

I have 2 ECU's...to test the CAN ports can I connect the 2 ECU's and have one writing and one reading? I'd like to do this in place of buying one of the controllers from Kleinknecht.

Are there any other good resources to help me get started?

Thanks in advance.

-Mike

Reply to
mike.a.james
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Hi. I'm not a CAN guru but can maybe point you in the right direction.

Is the project for research/study? If it was for a car manufacturer then you would be inundated with specifications related to 'their' specific implementation of CAN.

No. A node is the ECU itself.

or do the analog signals go to the ECU analog inputs and

Yes/No. There will be CAN messages defined by the car manufacturer which should be used to transmit various information. Normally you cannot just decide to send a message. The car manufacturer determines which signals (data in the messages) should be transmitted.

Are you using a Vector CAN kernel or writing one yourselves?

For basic CAN theory, maybe

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Reply to
Usenet Groups

Un bel giorno snipped-for-privacy@gmail.com digitò:

Have you considered to use other signals from the OBDII connector?

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OBDII connector has also the CAN pins, but I don't know how often they are used. Instead, K-Line and L-Line are supported by almost every 'new' car (I don't remember the years, it should be 1996 for US cars and 2001 for EU cars).

The normal sensors are connected to the ECU. The ECU acquires and processes the signals, and sometimes transmits some related data through the CAN bus. CAN messages have an ID and can contain up to 64 bits of data; the ID used and the format of the data is not standard, it's up to the ECU manufacturer to decide which data to send, which rate and which format to use. If you want to extract engine parameters from the CAN messages, you either have to find the CAN message mapping for your ECU (very unlikely), or you have to figure it out experimentally for yourself by using a CAN monitor and logging the messages.

As usual, you can start from Wikipedia:

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asd
Reply to
dalai lamah

CAN is not enough What protocol? Probably J1939, but there are several others. This determines what says what to whom and when.

Reply to
Neil

There's an excellent group: Archives and useful links:

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Reply to
Bill Davy

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