Logic probe for Can Bus

Papabravo

Joined Feb 24, 2006
21,259
That is also the behaviour of two-node network where the MCU on the receiving node has crashed. (The CAN module in the processor generates the acknowledge pulse not the CAN transceiver.)
That is correct, but I never said or implied that the transceiver was responsible for the Ack pulse.
BTW, a lonely node makes an excellent physical layer and cable tester.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
usually on the car we have more than 2 node and all of them ar working with the same protocol and different identifier.
But maybe in this case it will be nice if there's some kind of "magic box" who can make a kind of "map" who can show all the nodes. So I can see which node is missing.
 

Ian0

Joined Aug 7, 2020
10,021
That is correct, but I never said or implied that the transceiver was responsible for the Ack pulse.
BTW, a lonely node makes an excellent physical layer and cable tester.
Apologies - the sentence in brackets was for the benefit of the TS.
 

Ian0

Joined Aug 7, 2020
10,021
usually on the car we have more than 2 node and all of them ar working with the same protocol and different identifier.
But maybe in this case it will be nice if there's some kind of "magic box" who can make a kind of "map" who can show all the node. So I can see which node is missing.
It's called a CAN BUS sniffer. Mr. Google will find one for you!
 

Papabravo

Joined Feb 24, 2006
21,259
usually on the car we have more than 2 node and all of them ar working with the same protocol and different identifier.
But maybe in this case it will be nice if there's some kind of "magic box" who can make a kind of "map" who can show all the nodes. So I can see which node is missing.
Yes, a portable network monitor would be a most useful tool. it would allow network mapping along with node configuration and commissioning.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
I found this.
I'ts very cheap! I already heard can sniffer but since I saw very big price I never vent to read about it.... Is there any mode to transmit what I'm reading with can sniffer? I'm unable to properly test Lin alternator. I just turn fast them and after that they start charging. But I'd would like to interact with them.
 

Papabravo

Joined Feb 24, 2006
21,259
I found this.
I'ts very cheap! I already heard can sniffer but since I saw very big price I never vent to read about it.... Is there any mode to transmit what I'm reading with can sniffer? I'm unable to properly test Lin alternator. I just turn fast them and after that they start charging. But I'd would like to interact with them.
There are lots of things that are possible limited only by your imagination and skill. I'm thinking of an embedded controller with CAN and a UART. Then you can use a terminal emulator to talk to the embedded controller and have it interact with the CAN bus. Piece of cake.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
This evening I'm playing with the example on the last video. Every thing seems to be ok but I have nothing on serial plotter. Baud-rate is ok. The software "canhacker v2.0" recognize arduino but is not showing any data. I tried even with the jump for the 120ohm resistor. Tried different baud rate for the can.

Any Idea will be appreciate.
 
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Thread Starter

Mullins

Joined Dec 31, 2021
179
the final solution is very far from the original intent but remains simple and cheap. In some ways even better.
I bought a usb to can interface and I use it with Busmaster. It's sowing me all the node and the last message of each node. I also have the option to save the log. However if you leave the ground and only one Can cable the program stops reading.
 

PF Graham

Joined Sep 25, 2022
6
IView attachment 290865
This is a real CAN waveform, twisted pair cable about 2 feet long, terminated both ends, from a Microchip MCP2551 transceiver.
Anyone hoping for 0.5V to 4.5V levels is going to be disappointed.
(By the way, you don't need to remind me how hopeless my scope's real-time clock is - it gained over a year whilst the company was shut for Covid lockdown)
Ian0, do you have a way to contact you about how you set your scope up? I can't figure out how to DM you so apologies for sidetracking this thread somewhat - Thanks - Patrick
 

Ian0

Joined Aug 7, 2020
10,021
Ian0, do you have a way to contact you about how you set your scope up? I can't figure out how to DM you so apologies for sidetracking this thread somewhat - Thanks - Patrick
Dual channel scope, grounding clip on 0V at the transmission end. One probe on each of CAN+ and CAN-.
 

PF Graham

Joined Sep 25, 2022
6
Dual channel scope, grounding clip on 0V at the transmission end. One probe on each of CAN+ and CAN-.
What took you so long to reply....

Thanks, nube for sure on this site, I'll take the scope screen grab plus your reply and try to set up my stupid Rigol DS 1054z. I'm working on making a series of vintage Jeeps and making them plug-n-play EVs - and, of course, everything EV is controlled by CAN Bus. So, I had to make my own CAN Bus hub - shown here:1692908567968.jpeg

Old v.1 without twisted pair is shown in the upper right. New version in front.

Debugging from scratch is hell.

Any other help setting up my scope to get ANYTHING close to what you have on your scope would be very helpful.

Thanks - Patrick
 

nsaspook

Joined Aug 27, 2009
13,420
You can sniff CAN (and CANFD) with a cheap USB-logic probe and free software.
https://www.sparkfun.com/products/18627
1Mhz header, 5Mhz 64 byte data payload
1692912088905.png
pin header tap
1692912119711.png
Three CAN nodes and the logic sniffer. Linux PulseView with the USB device interface using the canbus decoder plugin.
1692912164695.png
captured 4 data packets
1692912200571.png
zoom
1692912221557.png
1692913371225.png
 
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PF Graham

Joined Sep 25, 2022
6
You can sniff CAN (and CANFD) with a cheap USB-logic probe and free software.
https://www.sparkfun.com/products/18627
1Mhz header, 5Mhz 64 byte data payload
View attachment 301172
pin header tap
View attachment 301173
Three CAN nodes and the logic sniffer. Linux PulseView with the USB device interface using the canbus decoder plugin.
View attachment 301174
captured 4 data packets
View attachment 301175
zoom
View attachment 301176
View attachment 301177
Wait, wait - I have a crazy crazy project picture too!
1692914721580.jpeg

A snap of my 1984 Jeep CJ-7 stock engine swap EVC project.

Also showing it to say I've got it torn up right now, working on a lift point for the stacked, 3 Tesla battery module (not shown in this picture, would sit on top of the front DC/CD converter and Pack charger - L to R).

Once I finish that so I can more easily lift heavy crap up, I'll put it back and test all your ideas on how to read my CAN Bus hub (pictured in the upper, Tech Box).

THANKS - Patrick
 

nsaspook

Joined Aug 27, 2009
13,420
Wait, wait - I have a crazy crazy project picture too!
View attachment 301178

A snap of my 1984 Jeep CJ-7 stock engine swap EVC project.

Also showing it to say I've got it torn up right now, working on a lift point for the stacked, 3 Tesla battery module (not shown in this picture, would sit on top of the front DC/CD converter and Pack charger - L to R).

Once I finish that so I can more easily lift heavy crap up, I'll put it back and test all your ideas on how to read my CAN Bus hub (pictured in the upper, Tech Box).

THANKS - Patrick
Don't forget the EMO switch. :eek:
 

Ian0

Joined Aug 7, 2020
10,021
With a scope, it's tricky to get anything more than a go/no-go result. I would suggest getting a CAN receiver IC (TCAN1051) and looking at the output, because you would get a much nicer waveform. Trigger on the negative going edge of RXD then adjust the timebase so that one complete frame goes on screen. If you can then zoom it (my Tek scope at home can, but my scope at work can't) you may be able to read some of the data. Don't forget that it uses bit stuffing to avoid runs of too many ones and zeros, so it's easy to make a mistake trying to read it.

At risk of digressing even further - what motor did you use? How much of the original transmission did you retain?
 

PF Graham

Joined Sep 25, 2022
6
With a scope, it's tricky to get anything more than a go/no-go result. I would suggest getting a CAN receiver IC (TCAN1051) and looking at the output, because you would get a much nicer waveform. Trigger on the negative going edge of RXD then adjust the timebase so that one complete frame goes on screen. If you can then zoom it (my Tek scope at home can, but my scope at work can't) you may be able to read some of the data. Don't forget that it uses bit stuffing to avoid runs of too many ones and zeros, so it's easy to make a mistake trying to read it.

At risk of digressing even further - what motor did you use? How much of the original transmission did you retain?
In a meager attempt to honor the OP's question of a down-n-dirty (go/no go) CAN Bus 'is it alive' detector, I'm not trying to do any of the CAN Bus reading of signal, I would just like to see my stupid scope represent CAN properly on the darn screen. If that cool ass TCAN1051 can do that, if you don't mind, a simple schematic would be lovely (please).

Digress, digress, the water's fine...

As to the second question; Hyper9 HViIS (A/C Synrm motor by NetGain - actually now made by Dana but that's another story). And yes, for my project, my plan is to make this a drop-in 'motor swap' with a new 'gas tank'.

Full modularization of the new parts (motor, battery modules, tech box, etc...), bolts into existing frame or cross member, no cutting or changing the drive train from the bellhousing back.

Here's the link to the project on the JeepForum site: https://www.jeepforum.com/threads/jeep-cj-7-ev-conversion.4455457/
1692954375907.jpeg

1692954412398.jpeg
I know what you guys are thinking - 'Boy, that guy sure likes to keep his drivers neat and tidy!' - right!?!

If you have any other questions that are more for this forum vs the JeepForum, I think out of respect for this site and the OP, we should start a new thread here - yes / no?

BUT, I'll be more then happy to answer anything you guys might like to know. The electronics of a this has been a complete blast to learn and change and do and ask and build and everything!

- Patrick
 
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