External CAN Source for LDS4

[littlestevie]

Hi,

I am having some problems "tapping" off my Vehicle's CAN bus for the LDS4. It seems that whenever the LDS4 is connected and powered up, the CAN Bus goes "down".

I have checked the wiring for the LDS4 and everything seems fine (I can power up the LDS4 and can send USB data to it). I have no problems reading off the CAN BUS using a 3rd Party CAN Bus monitoring device.

I use Port 1 and 16/32 CAN Code settings. An example of the the CAN arbitration ID, for RPM, is 12C(Hex) with RPM data in btye 4 and 5 respectively. I also set the CAN Bus speed to 500Khz.

For advice, please.

Thanks!

[RickS]

Hello,

This can be caused by a number of things. Something in the setup is wrong and upsetting the CAN. Even if the setup is wrong on the recieve side this can crash the CAN I'm not sure personaly how it does it but it can. I see you set the CAN speed on the LDS4 to 500Khz i presume this is the speed the vehicle bus runs at. Are you sending any messages out on the CAN outputs?

Thanks
Ed

[littlestevie]

Hi Ed,

I don believe I am sending any CAN messages out, as I have no CAN Outputs defined in the Setup. Yes, the CAN BUS runs on 500Khz. I must be missing something here....Any advice would be great....

Thanks!

[RickS]

Hello,

Does the LDS4 crash the can when you delete the CAN recieve messages?

Thanks
Ed

[littlestevie]

Hi Ed,

Yes it does. I even tried creating a new external connection for it, but to avail. It could be my wiring. Let me do a thorough check. Just to be sure, I am tapping the signal from the Honda F-CAN, running at 500kbps - CAN_H and CAN_L, and connecting the signals to the LDS4's Connector 1 - Pin 2 and Pin 7 respectively. Is the LDS4 CAN Bus speed setting of 500khz correct?

I am just a little puzzled.

Thanks for your help!

[RickS]

Hi

I think the problem is down to how you have the CAN codes justified - as you may be aware, a standard CAN ID is an 11 bit number but CAN controllers store it as a 16 bit number. Some CAN controllers store the 11 bit number left justified in the 16 bit number - this is termed a 16 bit CAN code in LDS4. Other controllers store it right justified, (an 11 bit code in LDS4).

In both cases, the underlying arbitration code is the same but it is written differently. Historically, GEMS has always written CAN codes as left justified (16/32) and this is the mode LDS4Editor defaults to. However, in industry (and in many CAN analysers) codes are written right justified. To set the LDS4Editor to work with right justified codes, go to the external source editor (Setup | Edit External Source) and set the radio button to 11/29.

I can see from your CAN ID 0x12C that this must be a right justified number
- bits 2 and 3 are set and this is not valid in a left justified CAN ID. So, if you set the external source editor to 11/29 bit mode and then put your CAN ID in as 0x12c, I think it will work - I have attached a setup modified in this way. Note that the left justified version of 0x12c is 0x2580!

Hope this helps
Ed