[Elecraft] K2 - KIO2 stop bit oddity

[Mike S]

At 02:14 AM 5/14/2008, Joe Planisky wrote...
>extremely erratically, presumably because it assumes 2 stop 
>bits.  The
>KIO2 manual says to use 2 stop bits, but that 1 stop bit will also 
>work.

That is only possible if the K2 firmware sends 2 and receives 1. Since 
the source code isn't available to check, Elecraft will have to 
respond.

Any device can send 2 (or more) stop bits, and any device can receive 1 
stop bit. The extra bit(s) will just be considered marking time (extra 
idle time between characters).

It would be strange for any modern device to require 2 stop bits. The 
option was originally used so that mechanical Teletype terminals would 
have enough time to cycle their mechanisms to an initial state between 
characters. That isn't an issue with any modern device (does anyone 
still use a Model 33 for RTTY?).

>If I set my terminal to 2 stop bits, I get garbled data about 70% of 
>the time. For example, the ID; command will return ID017, ID0, ID, 
>ID01, etc.

That looks about right for a mismatch. If the sender is only sending 1 
stop bit, the following start bit should result in a framing error, and 
NO character should be displayed. The inconsistency you see is likely 
the K2 marking time (busy with something else) between characters, 
which looks the same as the second stop bit to the receiver.