[Elecraft] Multiple devices on data interface?

[Jack Brindle]

Andreas;

>Can I connect multiple controllers/devices to the K2 simultaneously? I
>am thinking of Logging software and another hardware piece as a
>controller for a SteppIR antenna.  I think the answer is yes, just want
>to make sure.  Any things to be careful here?

Assuming that your question only pertains to the RS-232 port, you 
should be very careful connecting multiple devices to the K2. The K2 
can certainly drive multiple RS-232 receivers, meaning that a PC and 
another device or two could be connected to receive data from the K2. 
A very large problem occurs if you try to connect multiple 
transmitters to the K2's RS-232 port. Doing so could cause 
destructive damage to the transmit drivers in the external devices 
due to conflicting signal levels. Certainly the drivers would 
conflict, disrupting communications to the K2. There are controllable 
RS-232 drivers available which would allow busing of RS-232 
connections; few devices use these drivers making this option 
unavailable in your case.

So, you would really need to provide a small controller with multiple 
serial ports or switches which would allow the devices to "speak" 
without the potential for damaging each other's drivers. At the same 
time, it would need to provide arbitration to make sure that whenever 
one of the devices transmits, the receiver indeed does get the proper 
message. The K2 and other devices are not currently designed with 
protocols to support this, making the entire effort rather difficult.

Probably the best way to accomplish what you want is to use the PC to 
individually communicate with each device and to coordinate the 
information and forward it as needed. It's only a small matter of 
software, right?  :-) ;-)

-Jack Brindle, WA4FIB
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