At 15:37 05/05/97 +0000, you wrote:
>        Does anyone has some ideas on how to do a poor man's version of
>Plug-and-Play ? I need it to implement a network (maybe using RS485), and
>i want to insert nodes automatically, without the need for the person who
>plug's the node to know what's happening. Any ideas, comments ?...
>
>Thanks,
>Antonio Almeida

Hi Antonio,

   Have a look at the way ARCNET handles this problem. It's pretty good
providing you don't insert or remove nodes very often. It's on the SMC web
site somewhere, a web search should find it.

In short what they do is have a token which is passed around among the
nodes. When a node has the token it can initiate a transmission or pass the
token along to the next numbered node.

When a new node is added it will realise it is not getting the token. It
will then wait until the token is being passed and pull the network down,
destroying the token. The nodes then start counting until the lowest
numbered node times out and creates a new token. It then looks for the next
node to pass it along to which in turn passes it to the next and so on. This
process reconfigures the network to include the new node.

Quite neat, for a peer to peer network.

Hope it helps,

KEith.



==========================================================
Keith Dowsett         "Variables won't; constants aren't."

E-mail: kdowsett@rpms.ac.uk
   WWW: http://kd.rpms.ac.uk/index.htm