[WriteLog] Split Functionality for Com Port

[Eric Scace K3NA]

   I believe the constraint is that there are only 3 leads in the direction
from the computer to the radio: TXD, RTS, and DTR.  It is a challenge to fit
4 functions on three leads.

   TXD sends data to the radio serial port.  RTS is PTT.  DTR is CW.

   One might think: "Why not use DTR as FSK, too.  After all, the radio
won't be sending CW and FSK simultaneously."  The particular challenge is
the tight timing on the FSK keying.  My understanding is that some serial
port chips and their associated driver software may be a bit sloppy on
timing RTS and DTR, since those are usually changing states only very
occasionally.  Trying to key 45 - 100 bit/s might be a push, depending on
the machine's implementation.  I suspect Wayne and Ron did the 'safe thing'
to put the FSK keyline on the TXD lead -- which, of course, preempts TXD
from being used to run the radio data port.

   Another line of thought is: "Just send FSK when the PTT is keyed and the
radio is transmitting.  Send serial data to the radio when it is not
transmitting."  That could almost work with some external logic to direct
the TXD signal to either the radio's FSK jack or the serial data input pin.
But one can get caught in a situation where WL is partway through
transmitting something to the radio's serial port (e.g., a frequency poll
request) just when the operator wants to send FSK.  WL would have to
introduce a (probably slight) delay in order to finish the transmission to
the radio serial port before sending FSK.

   Which is why most people trying to do everything from one COM port break
down and use AFSK.  Sigh.

-- Eric K3NA

-----Original Message-----
From: owner-writelog@contesting.com
[mailto:owner-writelog@contesting.com]On Behalf Of Jim Reisert AD1C
Sent: 2000 July 16 Sunday 12:30
To: Mark Herson; writelog@contesting.com
Cc: Mark Herson; pvander@erols.com
Subject: Re: [WriteLog] Split Functionality for Com Port



FYI, DX4WIN sends CW on the same port that is used for radio frequency
control.  I don't know what it does about PTT, if anything.

I would *just love* if WriteLog could do CW, PTT, FSK and rig frequency
control from the same COM port!  Surely I must be living in some sort of
fantasy world, though.

73 - Jim AD1C

At 10:46 AM 7/16/00 -0400, Mark Herson N2MH wrote:

>Hello everyone,
>
>In WriteLog, is there any way to make a com port have dual functionality
>(ie, control PTT via RTS and RS-232 control of frequency)? From all the
>documentation I've seen, a com port can do either rig control (freq,
>etc.) or PTT but not both.


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