Re: Event triggered Sensor Nodes

Colin,

     CAN bus is an excellent choice for this type of system.  The beauty 
is that there is no wasted
bandwidth on the bus  because all received data is good data. Collisions 
don't corrupt the highest
priority message.  And in your system, transmitting only on data change, 
there should be plenty
of bandwidth.  The hardware will retransmit the delayed transmission 
once the higher priority message(s) is/are complete.

     Is there other traffic on this system?  I don't see why you are 
worrying about filters at all, as it
sounds like you want to collect ALL the messages coming in.  If so, you 
waste bandwidth by using
a common CANID.    Feel free to put data in the lower order bits of the 
CANID, if it gives you fewer
data bytes required in the message!

    You only need 7 bits for 100 nodes.  If you use an 11-bit CANID you 
can use the other 4 as priority bits if you chose.

     For belts-and-suspenders additions, you could consider a periodic 
node "heartbeat" message, in addtion to the event-driven messages, 
and/or master node message acknowlege back to the sensor node, to verify 
reception.   You can add a message sequence number in the data as well.

Rufus

On 1/19/2015 7:30 PM, Colin Watson wrote:
>
> Hi,
>
> Upon reading the MCP2510 data sheet, I am not sure how to set up a 
> data logging node to accept messages from about 100
>
> sensor nodes being animal feed bin weighers triggered by animals 
> entering and leaving individual feed gates.
>
<snip>
>
> *My experience with CAN bus is nil but it seems a good option for this 
> application.*
>
> **
>
> *An experienced comment would be immensely helpful.*
>
> **
>
> *Colin Watson.  Edinburgh*
>
> **
>
-- Rufus V. Smith FW Telematics 303 Norwich-New London Tpke. Uncasville, 
CT 06382 [email protected] (860) 848-6600 x 115

-- 
Rufus V. Smith
Faria Watchdog, Inc.
303 Norwich-New London Tpke.
Uncasville, CT 06382

[email protected]

(860) 848-6600 x 115