AVR-Chat

On 02/05/14 23:53, Mark Nowell wrote:
>
> Dave et al
>
> Background is that we have 20-year-old proprietary 485 protocol running at 9600,
> connecting up to 30 controllers over a mile or more, and we're looking to
> upgrade! A broad range of applications but primarily HVAC and building
> automation. Ideally I'd like:
>
> a) more bandwidth;
> b) isolation;
> c) greater address range;
> d) possibility of in situ firmware updates;
> e) 'seamless' connectivity with/through wireless nodes, repeaters etc.
> f) low hardware cost.
>
> CAN/CANopen is currently the front-runner, followed by Modbus, possibly BACnet?
> However I've read a few articles recently advocating "IP to the end-point" using
> small IP stacks that will fit in a reasonably low-level micro. IP sounds good.
> Ethernet? Application layer? I'm probably trying to convince myself this isn't
> the obvious choice it might otherwise sound.
>
> I'm interested in the various directions people have taken from the AVR. I've
> been looking at the Atmel Cortex-M3 range but I'm another one who has been
> clinging to AVR Studio 4.x. I've no experience of ST/NXP/Freescale/etc
> development tools so it's good to hear views on these.

If you run the SCADA DNP3 network protocol, you can keep all that old RS485 
stuff in a modern system. Every node in the network will have a simple address 
up to 64k nodes iirc. SCADA says nothing about what actual hardware comms layer 
is used. You can even have a heterogenous network by using suitable hubs to 
connect the different network types.