Can you recommend a good protocol for a RS485 network.

[Mozfet]

snap protocol

Hello.

I'm hesitating between the Modbus and the SNAP protocols.
Which one is better and why? I personally prefer SNAP,
because it looks easy to implement and it has lots of
examples for BS1 and BS2, which can be easily adapted
for Picbasic pro. But as I can see, most of the users
in this forum are commenting Modbus. Are there any
Picbasic examples for Modbus?

Another option is to use an 18F PIC with CAN controller.
What do you think about the CAN networks and its protocol?

What would you advice me?


Thanx.
Mozfet from Sofia.

 

[sam_manchali]

hi,
i had implemented my own protocol over the RS485 bus, with a round robin method , one master pic and 6 slaves. i had used the addresable USART in '877. it works superbly ( not much data transaction for my appli) .
Can is a good bus where the data is v important. its CRC helps a lot for data error detection , so i would recommend CAN bus. i had used SJA1000(philips) over 8051 , found it a complex protocol , with normal and Pelican modes ( dont konw if they are avaliable in the 18f series....)but if data is very critical , then i think u ought to go for CAN.
regards
sam