Problems with CANcasXL and vxlapi.dll

[YogeshShivarudrappa]

Hi Troy,

Going forward from the discussion below,

https://decibel.ni.com/content/docs/DOC-30180#comment-30021

I am able to transmit STD and XTD id CAN messages with 33.333kBaud.

But the same with 500k Baud is not working. I am not getting any error from the xl library, instead i get stuff error.

For more information, please look at the screenshot attached.

Any help is appreciated.

Thanks,

Yogesh

[nathand · Accepted solution]

Are you sure the sending device is also configured for 500k? Have you tried any other speeds? Is the CAN network terminated properly?

[TroyK]

You are evidently using another program to check that the CAN messages are being transmitted correctly and that is where the error is being displayed?

So the vxlapi library is not returning any errors? Is the red error light on the CANcaseXL displayed?

I would look at your hardware setup. The reason your setup may work at 33.33k and not 500k could be a non compliant bus configuration. (Assuming all nodes are set to the same baud rate as Nathan suggested.)

How long are the wires? Are they twisted appropriately? Do you have any termination resistors on them?

Perhaps you could describe your setup in a bit more detail.

[YogeshShivarudrappa]

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@nathand wrote:

Are you sure the sending device is also configured for 500k? Have you tried any other speeds? Is the CAN network terminated properly?

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All the nodes are at 500k Baud. The problem was with the terminating resistors. After including a 120ohm terminating resistor, I am able to communicate over high speed baud rates.

Thanks for bringing that point nathand.

Thanks,

Yogesh

[akhiltel]

Hi Troy,

My case is similar to that of Yogesh's, but not the same. 

hardware : Cancasexl. 500 KBD. 

I am trying to transmit CAN messages to cancasexl using labview. I am getting error frames in between the proper communication. It means, red LED of error also blinking once in a while in CANCASEXL.

I tried to check what is that error, took another cancasexl, looped it back from the one that connected to lab-view pc, and tried to monitor using canalyzer.

It showed :

Stuff Error, Segment : Data/ CRC Sequence / ACK Delimiter.

The segment was changing with the things mentioned above.

Another interesting observation was that, the rate of the error frames in this setup is higher than the last mentioned one.

Very grateful to any suggestions that will bring me out of this conundrum and make my VI perfect. 

[TroyK]

And you've tried the solution found by the OP? Make sure the bus is properly terminated. It sounds like the same problem.

Without proper bus impedence, reflections cause interference especially at higher bitrates like 500KB.