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Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!un!pc012 From: pc012@un.seqeb.gov.au (Patrick Collins) Subject: Serial Comms for Half Duplex Operation Message-ID: <D4zwtC.420@un.seqeb.gov.au> Organization: SEQEB X-Newsreader: TIN [version 1.2 PL2] Date: Mon, 6 Mar 1995 01:43:58 GMT Lines: 33 Can anyone give me any pointer on how to hack the FreeBSD-1.1 or FreeBSD-2.0 comms stuff so that it can be used on a half duplex link like RS485 (EIA-485) or a half duplex radio link. The following operation woulld be required. * When I want to transmit check CD, if CD is asserted wait a small random time for it to be deasserted (p-persist method). * If CD is deasserted, assert RTS and wait for CTS to be asserted. * When CTS is asserted transmit block of data. * At completion of transmission deassert RTS. I don't expect someone to write this code for me but could someone please let me know if this is even possible and if so which files would need to be modified and approximately what functions, etc. If I can get this working I will post the diffs back here. I intend to use this facility with both a network of PLC's on a RS485 line and with Motorola Darcom DFM half duplex 900 MHz radio system. If anyone would be interested in taking this on as a project (preferably someone in Australia) please let me know. Thanks. -- ----------------------------------------------------------------------------- Patrick Collins - Communications Design Officer email : pc012@seqeb.gov.au The South East Queensland Electricity Corporation phone : +61 7 223 5237 2 Bowen Bridge Rd, Fortitude Valley, 4006 fax : +61 7 223 5059 Queensland, Australia (Best State, Best Country) Viva el Cristo Rey ! -----------------------------------------------------------------------------