[GreenKeys] TTY to Ethernet Converter or TTYoIP

[Keelan Lightfoot]

John,

This is why I switched to the Xport Pro -- I have the source for all parts of the system, and complete control over all aspects of its operation. The sample serial to ethernet application, 's2e' allows for tuning the timeouts out of the box, and the buffer sizes can be tuned quite easily as well. I'm tweaking things at the driver level to get the UART to speak at 45.45 baud; it's not a big leap to change other things to optimize character-at-a-time performance.

The 's2e' application supports both a client and server mode. Given that most folk these days are hiding behind a router of some sort, the server mode would not be too useful, not without messing about with port mapping and firewall rules. An external server would allow connecting two or more 'TTYoIP gateways' operating in client mode together with minimal shenanigans.

The server that I've roughed out supports connections from multiple clients into a single 'virtual private wire'. The server handles rate limiting traffic so that even if the combined input to the server exceeds 60 WPM (or 66 WPM, or 100 WPM), the output from the server to each client will always be 60WPM. Instead of buffering, the server just drops any characters in excess of the 60 WPM rate. Basically, if more than one person is typing at a time, the output of the circuit will be garbage; mimicking a real loop.

- Keelan

On 2011-08-02, at 9:33 AM, John Nagle wrote:

>     This seems like a good device for that.
> 
>     Remember to turn the gap time and the buffer size way down.  The
> device has an accumulation timer, which is, by default, 4 character
> times.  If you leave it at the default, there will be a delay of 4
> character times between hitting a key and having it sent.  At 45 baud,
> that's seriously annoying.
> 
>     The default buffer size is 2048 chars, and if left at that size,
> when you interrupt output, you get to wait for the remaining 2048 chars
> to print.  I went through all this with USB to serial converters.  It
> can all be made to work, but the modern defaults are far too big. 			
> 
>     The Xport device, by default, is set up as a client, not a
> server. It will need to be reworked so that it initiates connections
> to some external server on its own.   If you can do that, you can
> eliminate the need for an external computer.
> 
> 				John Nagle
>