I agree with the preference of using hardware flow control if possible. I
don't remember where but somewhere I read (and learned by experience over 20
years in my daytime job) that 9600 baud was the limit for software flow
control on three wire circuits.... something about turn around time in the
UART of the serial interface. But we digress as in this application there
isn't enough data coming from the interface at a fast enough rate to fill a
buffer and drop bits.
Gary - AB9M
--------------------------------------------------
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Sent: Saturday, January 31, 2009 11:11 AM
To: <tentec@contesting.com>
Subject: Re: [TenTec] Ham Radio Deluxe
> On Sat, 2009-01-31 at 09:03 -0500, Ed wrote:
>> CSM(r) Gary Huber wrote:
>> > Note; if you choose to use only DB-9 pins 2,3, and 5 for signal, you
>> > must
>> > use 9600 baud and below speeds with software flow (XON - XOFF) flow
>> > control.
>> >
>>
>>
>> Thats strange, I only use 2-3-5 and 19200 and all works perfectly. I
>> must have missed the above somewhere.
>>
>> Ed W3NR
>
> Ordinary communications software is much happier if on the 25 pin
> computer end that pin 4 is connected to 5 (RTS/CTS hardware handshake),
> and pin 6 is connected to 8 to 20 (Data Terminal Ready hooked to Data
> Set Ready and Data Carrier Detect). And on a 9 pin I see RTS/CTS
> requires jumping pins 7 and 8. DCD to DSR and DTR needs pins 1, 4, and 6
> connected. XP and VISTA may not allow serial communications without
> those jumpers because they resist software connecting direct to the
> hardware. Their port drivers are set only for a real modem. Ham control
> software may ignore those bits, but only when it can get directly to the
> hardware when the OS allows that. Standard communications software uses
> those lines to determine if there is a truly a modem on the wire and if
> its connected, or needs to be told to connect before data can be moved.
>
> Then I've read on this forum that OMNI V or VI had a problem with
> whether they were connected as a Data Set or a Data Terminal. If a Data
> Set the cable is straight, if Data Terminal the cable signal wires have
> to be crossed, e.g. null modem cable. I've also read that one of these
> OMNI is easily corrected to Data Set connections by inverting an
> internal connector.
>
> Two Data Terminals (computer is always connected as a Data Terminal)
> connected with a straight cable will NOT communicate.
>
> 73, Jerry, K0CQ
>
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