Dan, It would seem to me that the issue here would be that the TNC's are not individually addressable, thus two TNC's listening to a single radio will both hear the signals from the sending TNC/radio combination and both will try to act on the signal, unless the sending radio uses two different speeds, and the two TNCs operate at differing speeds.
Since you stated that you wish to talk to two different controller serial ports, why not use a single TNC output to a switch thru which you will then connect to the RS-232 device that you wish to talk to. The switch could be a DTMF controlled relay setup or could be controlled via the RS-232 stream. I have seen the RS-232 controlled setup back in the days of Motorola's CoveragePlus SMR systems. We dialed a single modem at the site, then issued a command to connect to one of 3 or 4 different devices. When finished with one connection we disconnected from the device and could then connect to another. It's been a while since this system was operational but the concept would be the same as what you are trying to do. Milt N3LTQ ----- Original Message ----- From: "Dan Blasberg" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, August 02, 2007 10:22 AM Subject: Re: [Repeater-Builder] Re: Connecting Multiple TNCs > The only schematics I have seen are for connecting multiple TNC's to > the serial port on a computer using diodes on the data lines. > > If anyone happens across a schematic (That work) for connecting > multiple TNC's to a radio, I would also be interested. > > Dan > KA8YPY > > > On Aug 2, 2007, at 9:26 AM, Duane Hall wrote: > >> I remember seeing the schematics you are talking about, they were >> over on www.packetradio.com. I cant find them now, but they are >> probably there somewhere. >> >> Duane >> AB8QU >> >> Dave Novotny wrote:Hi Eric, >>> >>> I'm not too worried about lots of packets perhaps >>> interfering/colliding with each other. I have a couple of repeater >>> sites with two controllers. I want to have remote control of each >>> controller. I don't want to share the RS-232 side. I'd much rather >>> share the RF side. The circuit was pretty simple. It used diodes >>> on the PTT for isolation and resistors to mix the TX audio. I'm not >>> sure if there was any other control or not. >>> >>> Dave >>> --- In [email protected], "Eric Lemmon" <[EMAIL PROTECTED]> >>> wrote: >>> >>>> Dave, >>>> >>>> I'd like to see that article, too. Connecting two TNCs to one >>>> >>> radio is >>> >>>> easy, but allocating the RX and TX functions between two devices >>>> >>> is hardly a >>> >>>> trivial matter. Unless a buffer is used to store outbound data >>>> >>> while the >>> >>>> radio is busy receiving data on the other TNC, collisions will >>>> >>> occur >>> >>>> regularly. This should be interesting! Is this a good idea? >>>> >>>> 73, Eric Lemmon WB6FLY >>>> >>>> >>>> -----Original Message----- >>>> From: [email protected] >>>> [mailto:[EMAIL PROTECTED] On Behalf Of >>>> [EMAIL PROTECTED] >>>> Sent: Wednesday, August 01, 2007 4:51 PM >>>> To: [email protected] >>>> Subject: [Repeater-Builder] Connecting Multiple TNCs >>>> >>>> Hi all >>>> >>>> Some time ago, I saw an article on how to connect two TNCs to a >>>> >>> single >>> >>>> radio. Does anyone remember such an article an either have a copy >>>> >>> or point >>> >>>> me to a site where I can download it? >>>> >>>> >>>> >>>> Thanks, >>>> >>>> Dave, WA6IFI >>>> >>>> >>> >>> >>> >>> >>> >>> >>> Yahoo! Groups Links >>> >>> >>> >>> >>> >>> >> >> > > > > > > > Yahoo! Groups Links > > >
