At 12:49 PM 5/28/99 -0400, you wrote: >Carlos: > >What about using RS232 in a multi-drop or star configuration? I though >RS232 was point-to-point. > It usually is. For multi-drop, try RS485. There is an IEEE standard (1118 I think) that defines an address and packet system for talking to multiple black boxes. Basically, the first byte is 9-bits and contains the address, and the subsequent 8-bit bytes contain the data. As soon as a pause in the data stream occurs, or the packet is complete, the receivers must switch back to watching for the 9-bit address again. Supposedly the UARTS in the newer PICs support this. We are looking at doing a system with 100+ data loggers spread down an 18,000 foot long structure with a repeater every few thousand feet. The wire will end up costing more than the electronics :_p. If anyone has implemented this protocol in a 16C7xx or similar, I would sincerely appreciate a copy of the code or a point to it. Kelly **************************************************************************** ******** All legitimate attachments to this email will be clearly identified in the text. William K. Borsum, P.E. OEM Dataloggers and Instrumentation Systems &