[Elecraft] [KX3] RS232 xcvr control when serial ports are occupied

[Stephen Rector]

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 <donwilh at embarqmail.com> 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?