Sorry about the pin typo. Look at the cable link for the steppIR that
Dick K6KR sent and that will be obvious. I was looking at that diagram
when I typed my response, but did not proof it.
TXD is really pin 3.
73,
Don W3FPR
On 7/8/2018 7:24 PM, Stephen Rector wrote:
Don:
I tried a 3.5mm Y-connector at the KXPA and this did not work. But based on
your feedback and also that of N6TV, I see that I have multiple TX drivers on
the TXD line. Even if there is no TX from the antenna controller, the
low-impedance of its TXD driver will load the line. Bob also thinks the
controller may be polling for info, much like the program FLRIG does. One
correction to your info Don, I think TXD is pin 3 on the DB-9, and not pin 2.
The KXSER cable DB9 shell appears to be molded - it's not obvious how to
disassemble it. So I will need to go into the controller to disconnect TXD
there. I'll report back on whether or not that works, next weekend.
73,
Steve, NU7B
On Jul 8, 2018, at 2:22 PM, Don Wilhelm <[email protected]> wrote:
Steve,
Yes, since you are using both the KXUSB and the KXSER cables, a "Y" at the
KXPA100 would serve you well.
If your magloop controller also attempts to transmit, you can remove the
connection to pin 2 on the DE9 end of the KXSER cable (just remove the
backshell and disconnect the wire).
RS-232 multiplexors are complicated devices and require the use of the full
RS-232 bus (mainly DTR and CTS signals) to handle the handshaking signals. The
3 conductor KX3/KXPA100 wiring will not provide the proper handshaking signals.
The handshaking signals are not provided from the data stream (as they are in
Ethernet and other communications protocols), but from the explicit signals
separate from TXD and RTS.
Note that the KX3 (and most other Elecraft products) rely only on TXD and RTS,
which are reserved for data transmission only in the RS-232 scheme of things.
73,
Don W3FPR
On 7/8/2018 4:56 PM, Stephen Rector wrote:
Hi Don:
Yes - it occurred to me after sending the post that I might be able to create
the split at the KXPA with a stereo Y-cable/connector. I am using a KXUSB to
the computer, with a KXSER cable going from the the antenna controller to the
KXPA. It is the KXUSB that presently has no place to connect to.
So - I think I can try a 3.5mm stereo y-junction at the KXPA. Hopefully
impedances won't be an issue at 38400 baud...
I did look for RS232 multiplexers - they seem to exist for industrial
applications. The documentation seemed to be sparse on the web.
Anyway - thanks for the pointer :)
73,
Steve NU7B
On Jul 8, 2018, at 1:37 PM, Don Wilhelm <[email protected]> wrote:
Steve,
Are you using the KXUSB to connect with the KXPA100/KX3, or are you using the
KXSER with a real computer serial port or a USB to serial adapter?
Since your magloop controller only 'sniffs', it means it should only listen and
never try to transmit on the RS-232 signal lines. If it only listens, there
will be no collisons (RS-232 is not packet oriented, but an asynchronous
communications system).
If the magloop controller also transmits on the RS-232 bus, you will need some external
device to act as "traffic cop" - note that RS-232 is a point to point system
(unlike Ethernet and others) where there is one driver device and one receiver at each
end.
So yes, you can use a splitter - one with a 3.5mm stereo plug and two 3.5mm
stereo jacks if using the KXUSB.
If you are using the KXSER cable instead, yes, you can connect a "Y" DB9 splitter to the
DB9 end of the KXSER cable - the computer connects to one side and the magloop controller connects
to the other side of the "Y".
On 7/8/2018 3:31 PM, Stephen Rector via Elecraft wrote:
Hy home station is a KX3 + KPXA100, and I can control the radio via the RS232
port on the KXPA. However, recently I added a Ciro Mazzoni magloop to the
station, and its controller plugs in to the KXPA serial port to sniff for
frequency information, allowing re-tuning on the fly. This leaves no RS232 port
left for remote control of the radio.
How do I modify this arrangement to add an extra serial port for KX3 control?
My first thought is that, since the antenna controller just sniffs for data, I
could add a DB-9 Y-cable to provide the extra port at the controller serial
port location. However, packets could still collide ...does the protocol handle
this? Is there some sort of multiplexer available?
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