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

[Don Wilhelm]

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?
>