| Author |
Topic |
|
|
opsens_claude_belleville
34 Posts |
 Posted - 31 Aug 2005 : 17:38:01
|
Hi
I would like to know how to configure the CAN driver to use 11bit ID instead of 29bit ID like explain in the WinCE PeliCAN Driver Spec v1.4
Do I only have to change the CAN_MSG structure in CANApp.h
ULONG addr_id to something like INT addr_id
Because I don't see how to configure it via IOCTL.
All my other CAN devices use 11bit ID and the CAN speed is critical for us
with 29 bits ID packet size is min 64bits to max 128 bits
with 11 bits ID packet size is min 44bits to max 108 bits
The CAN seem to have alot of overrhead
I need 16 devices at 1kHz each
Each data is encode into 16bits
If I use 29bits ID, I encode the data into the ID, so I got
1'000'000bit/s / 64 bits = 15625 packet/s so at 1kHz = 15devices
If I use 11bits ID, I encode the data into the data field, so I got
44bits + 16bits = 60bits instead of 64
1'000'000bit/s / 60 bits = 16666 packet/s so at 1kHz = 16devices
Like U see I'm kind of short
I have other solution like sending 2 data per device per message
Thanks
Phil
Opsens |
|
|
akidder
1519 Posts |
Posted - 08 Sep 2005 : 14:12:44
|
To accept 11-bit identifiers, I believe it's just a matter of setting the acceptance filters (ie. mask off the unused 18 bits). Take a look at topic 516 for some pointers about transmitting 11-bit identifiers.
While I think you can talk to 11-bit devices using the 29-bit mode, I'm not sure this solution will give you the shorter message length you're looking for. You might need the BasiCAN mode, which our driver doesn't currently support.
Your design seems pretty close to the edge of being able to work reliably. You should probably look at a design that gives you wider margins, especially if the information each device is transmitting is critical. The isochronous transfer mode of USB might be a solution that would give you the throughput you need, though in that mode, it's possible to drop samples. The solution you choose really depends on your application.
Let us know how we can help. |
 |
|
| |
Topic |
|
|
|
All Forums
Hardware
Configure CAN to 11bits message identifiers
Forum Locked
Send Topic to a Friend
Printer Friendly