Chris Carr wrote:
>
> I have only been half following this thread so my apologies if I have got
> hold of the wrong end of the stick.
>
> I have implemented a somewhat similar system on RS485 using a Slotted Aloha
> Protocol. It works very well  on low throughput systems and is quick and
> cheap to implement.
>
> I was originally going to use CAN for the system and even invested in a
> MCP2510 Development Kit. Only then did we get the Standards and when we
> started reading them it slowly became clear that CAN is only a transport
> media same as RS485 (except it includes error checking, collision detection
> etc etc) You still have to overlay it with a Communications Protocol. The
> idea of using CAN was rapidly dropped as the complexity could not be
> justified for that project.

I'm not familiar with Slotted Aloha, can you provide more details?

Implementing a comm protocol on top of CAN doesn't look that difficult,
but I could be missing something. If I was going to use 485 I'd have to
write the adressing/arbitration protocol and the comm protocol. Only
having to write one of those sounded a lot easier to me. Then again, I
don't know what slotted aloha involves. Since I'm going to be
transmitting mostly event based information, the CAN method of typing
messages as opposed to addressing them is appealing.

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