On Sat, 2009-01-31 at 12:47 -0500, Ed wrote:
> Dr. Gerald N. Johnson wrote:
>
> > Ordinary communications software is much happier if on the 25 pin
> > computer end that pin 4 is connected to 5 (RTS/CTS hardware handshake),
>
> TT does not use rts/cts....you might be thinking of Kenwood that does.
Please read what I said, that you quoted above. "the 25 pin COMPUTER
END" The jumpers I suggest are ONLY on the computer end of the cable.
>
I've been using and programming RS-232 ports since about 1975. RS-232
rules are often ignored, but are as often rigidly enforced by the more
recent operating systems that don't simply allow user software direct
access to the serial port hardware that was easy in MS-DOS. The
purveyors of Windoze believe they know more about our use of the serial
port and so lock it up with their serial port driver that enforces
RS-232 rules, though the hardware works fine without following RS-232
rules and that's how many radio interfaces are built.
RS-232 demands that a data terminal device show its ON by asserting DTR.
RS-232 demands that a date set device (e.g. modem) show its alive by
asserting DSR when it receives the DTR signal.
RS-232 demands that a data terminal devise asserts RTS and that it
receives CTS from the data set before it sends data. RS-232 also wants
the data terminal device to detect DCD from the data set to signify that
the modem is connected to another modem and so the data communications
path is working, that the data path extends beyond the local modem.
Standard serial port driving software does all of that. The serial port
HARDWARE is more versatile. The jumpers applied to the computer end of
the serial cable simulate the handshaking of the data set to all
software including the fancy port drivers and often makes three wire
serial communications work quite fine providing the controlled device
can accept all the data tossed at it or that if it misses a command, its
not destroyed or put into orbit by missing that command that can be
repeated if missed or misunderstood. Handshaking is often instituted to
prevent such errors, either hardware or software. Hardware requires two
more wires in the cable and the logic included in the device hardware
and software, software requires the software in both units be prepared
for XON/XOFF in the data string and to not be sending any arbitrary
binary data that might inadvertently include those binary characters.
The most recent windoze versions don't even believe in RS-232 ports or
in allowing user software direct access to the hardware when added, and
that makes serial communications programs not work when the jumpers are
NOT in the computer end of the cable when the radio itself does not
support those hardware handshakes. Which makes those two jumpers vital
to having the controls work.
>
> > 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.
>
>
> The Omni5 requires a null cable.
>
> The Omni6 requires a straight through cable.
>
> Pins 2-3-5-7 are all that are needed.
Why 5? On a 25 pin cable that's CTS.
>
> The baud rate is not dependent on the serial port. It is determined
> between the radio and the rig control software.
The data rate IS MOST DEFINITELY dependent on the serial port. The clock
speed MUST match at both ends or data is not understood. The modern
computer serial port is capable of speeds from 45 baud to at least
115,200 baud, but the serial program working directly or with the OS can
set it to many speeds based on dividing a fixed frequency clock. Because
of that divider, the higher speeds tend to be in ratios of 2:1.
>
> You guys are making this much harder than it really is.
>
> This is all discussed and thoroughly explained in both manuals.
>
> If you own an Omni5 you will need a N4PY chip.
>
>
> Ed W3NR
>
>
73, Jerry, K0CQ
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