AVR-Chat

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.

Thanks,
Mark

On 02/05/2014 04:18, Dave McLaughlin wrote:

Hi Mark

There are a number of protocols to choose from and they depend on whether this is for home or commercial use.

CANBUS Nice and reliable and easy to use once you understand the basics. No licensing issues if you use devices with CAN built in. FPGA with CAN requires licensing. Protocol information freely available. Many PROTOCOLS are based on the CAN hardware layer. Some free. Can use your own if only you r devices on the network.

MODBUS Very old and can work on RS232, RS485 or Ethernet (TCP protocol - that even works over a GPRS connection) Many libraries out there and again, like CAN, no licensing issues and protocol free. This is a great protocol and just works. I have a Variable Speed Drive connected to a 40KW motor that is controlled via MODBUS on an Android device. Libraries for almost all languages are out there.

CANOPEN Industrial and some free libraries. Runs on CAN Bus and an established protocol.

HART Industrial protocol for sensors on 4-20mA loop but expensive to license unless you are going to sell lots of devices. Even just to get the protocol docs to read devices is 1000's of dollars. I have a very small project for this but stalled at this time due to the licensing costs.

These are just sample of what I have looked at or used recently. There are many more like PROFI-BUS etc. Do a Google search and you will get lots of hits and when you find one you like, come back and post to see if anyone knows about it.

Good luck with the project. (assuming you have one in mind)

Dave…

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Very funny Scotty, now beam down my clothes…

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From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf Of Mark Nowell
Sent: 01 May 2014 19:13
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Where has everyone gone?

like-minded engineers in a discussion about choice of network protocols for industrial controls.

Thanks,
Mark