Where can I find algorithm for RS485 network communication?

[otakung]

I want to use about 5 microcontrollers and connect them by RS485 with "network type". I don't know how to call it, it don't have master and slave, all uC can start communication with any other uC. I can't specific to some words so I can't search effectively. Thank you for your suggestions

 

[C-Man]

Re: Where can I find algorithm for RS485 network communicati

RS485 is only the hardware standard, you can do your own protocol or use a standardised one like modbus www.modbus.org

If you are using a PIC processor you can find a lot of information at the CCS forum www.ccsinfo.com/forum use the searchfunction there.

best regards

 

[gorkin]

Re: Where can I find algorithm for RS485 network communicati

See the following link :

**broken link removed**

Gorkin

 

[Ajay]

Re: Where can I find algorithm for RS485 network communicati

Actually, you need a token ring passing protocol where each micro must wait it's turn before it can speak. So, basically, you need the following:

0. Each micro must have a unique address
1. logic to claim token: Say, x ms times the node address wait time before a token is claimed
2. Once the token is claimed by any of the micro's, sent a frame. Find/create a successor. If there is no data to be sent, pass the token to the successor. If successor not found, send token back to the earlier node.
3. Define maximum node address so that after that address is solicited, send the token back to the first node.

If you do not want to do the token ring passing network, you need to create a master/slave configuration where one master arbritrates the data traffic.

Another way is to use a prioritized network such as CAN and use the CANopen protocol on top of it.

Have I confused you enough yet?!!

Ajay

 

[otakung]

thank you for you all
I understand a little more. But at least I get some idea to find the information and learn it.
thank you very much