CAN MSG PAYLOAD: Will I need to configure for 2 bytes if I need a 9 bit msg

[nathand]

Each element of the payload array represents one byte. That's all. You can view that byte in decimal, hex, binary. You might find it helpful to right-click the numeric constant (the blue-bordered payload array element) and show the radix, then click the 'd' for decimal and change it to 'b' for binary.

[sfrosty]

In response to your statement:

Your "CAN MSG Properties" image is on the right track. The only thing unknown here is the placing of the data in the message: you might stuff 2×9 bits like you do in your "message overview" - but I guess using 16bit entries for each accelerometer value is more probable…

After looking this over, it appears to me that using 9 bit entries would be somewhat complex and 16 bit entries would be the better way to go. Do you agree? Thanks!

[GerdW]

Hi sfrosty,

when I can design my own CAN messages I try to stay at byte boundaries, using bytes or words per signal.

In case I'm limited in "space" (available message IDs) I also use nibbles (4bit entities). When there are single bits (like error flags) I stuff them in one byte.

In your case I would either use 3 words (16bits per signal) or 3× 12bit signals using 48 or 36 bits of the full 64bit frame…

[sfrosty]

Kool!

How's this:

attached

[GerdW · Accepted solution]

Hi sfrosty,

now it looks ok - as I suggested using 3× 16bit signals…

Good luck!

Edit: to manage CAN message definitions I can recommend CANdb++ from Vector. This tool is available for free!

[sfrosty]

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@GerdW wrote:

Hi sfrosty,

now it looks ok - as I suggested using 3× 16bit signals…

Good luck!

Edit: to manage CAN message definitions I can recommend CANdb++ from Vector. This tool is available for free!

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Just wanted to Thank You again!!!!! from sfrosty

[sfrosty]

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@nathand wrote:

XNET Read returns an array of frames - an array of clusters, where the cluster structure represents a CAN frame, and each frame is one array element. Within the frame cluster, the "payload" element is an array of up to 8 elements. So, when you tell it to read N frames, you get an array of N clusters, and each cluster contains a payload of up to 8 bytes.

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Just wanted to thank you again! from sfrosty