Need Oscilloscope and help for checking CAN

**borshch** · 27th August, 2018, 04:02 AM

I’m looking for Oscilloscope for checking CAN lines. Also with the ability to have a saved “known good” graph to compare to the can waveform thats being read.

**Aajii** · 27th August, 2018, 05:42 AM

Originally Posted by borshch

I’m looking for Oscilloscope for checking CAN lines. Also with the ability to have a saved “known good” graph to compare to the can waveform thats being read.

If you want to study/test CAN lines, better to have also CAN analyzer.
With it, you can see is bus alive, and what messages are transmitted.
You can also generate your own CAN messages with CAN analyzer.

**borshch** · 27th August, 2018, 05:51 AM

I’m looking for a type that I can check can lines on a vehicle for example: if there is corrosion on can wires or intermittent signal or faulty module messing up a can network etc

**Aajii** · 27th August, 2018, 09:04 AM

One basic measurement is with multimeter:

CANbus voltages (canh/canl) are approx. 2.5V measured betweem CAN - GND with multimeter.
Normally voltage should be between 2.0 V - 4.0 V.
If it is lower than 2.0 V or higher than 4.0 V, it is possible that one or more nodes have faulty transceivers.

If you want to measure with oscilloscope, electronic oscilloscope is good.
My opinion is that Rigol scopes has good price/quality

**gljuk** · 27th August, 2018, 01:41 PM

Actually, you need no example charts of can bus, since they are very clear and simple.
It must be something like this:

The "data" is difference between CAN-H and CAN-L signals, which must be about 2.5V

**Mr Mo** · 28th August, 2018, 01:25 AM

PICO SCOPE is what u should read about

**borshch** · 28th August, 2018, 01:31 AM

Whats the minimum bandwidth MHZ for a scope for can data analysis ?

**clusters** · 28th August, 2018, 01:36 AM

Any automotive scope is adequate, but like previously stated you can do it with a meter.

You won't be able to decipher any detail in a CAN signal, just verify the operating voltages.

First you need to know what system you are working on, UART, hi speed or lo speed CAN, PCI Bus, CCD Bus, one wire, two wire, they are all different.

I repaired a Caravan no start dead dash CCD Bus problem with just a meter, the process is the same for all, disconnect modules till the bus goes normal.

In my case, CCD Bus was 2.5V key OFF with the door open and BCM awake to control the interior lights, key ON it was 9V

Turns out the HVAC panel had a cold solder joint on the ground pin, which caused the module to seek a ground through the CCD Bus taking down the whole van.