AVR-Chat

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 your 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…