Encontre esto en
http://www.lvr.com/spc.htm 485net.zip (100k) contains VB5 program code and a schematic for an RS-485 network. The master node is a PC running Visual Basic. The slave nodes may be Basic Stamp IIs or PCs. The code and schematic are excerpted from Serial Port Complete.
Espero que sea de utilidad
Saludos
Luis
