On Tue, May 12, 2009 at 10:57 AM, solarwind wrote: > On Mon, May 11, 2009 at 10:46 PM, Xiaofan Chen wrote: >> I think the easier way is not to use RS485 and invent your own >> multi-master protocol. For example, in the previous threads, >> CAN or Ethernet are both recommended. > > What do you mean? Isn't RS485 the physical layer specification? I'm > going to write my protocol over RS485. I mean it is more difficult to define your own collision detection/avoidence protocol for multi-master RS485 than to switch to CAN/Ethernet. >> It is possible to make RS485 multi-master but the hassle may not >> be worth the efforts. One example here: >> http://www.keil.com/forum/docs/thread8794.asp > > It was done with CAN via a twisted pair half duplex line, so I want to > try to do it over RS485. For hobby purposes and low speeds, I should > be able to cook something up. -- Xiaofan http://mcuee.blogspot.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist