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TCP-group 1992


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TTYLINK, OSI layers and POPCORN



> >Has anybody tweaked the ttylink code to allow a ttylink connection (telnet
> >port 87) to be re-directed to a COM# async port? My reason for wanting this
> >is to allow access to a RS232-equipped instrument to be accessed over the
> >network.
>
> It doesn't work that way.  Port 87 and Port COM1 are not the same kind of
> "port" at all.  The async port is really a port, accessed at protocol
> layer 1 (physical).  The ttylink port is more a "socket" and has meaning
> only at protocol layer 4 (transport), where TCP runs.  I assume you know
> this, Tom, but I wanted to get that out of the way before massive
> confusion resulted on the part of readers who may not be familiar with
> ttylink and what it is.
>
> Of course, ttylink will route across an asy interface if there is a
> TCP/IP host at the other end running SLIP or something like that, but
> this is not what you are asking.
>
> There is a "comm" command which just dumps a short piece of raw data
> out to the interface, which is useful for things like putting a TNC
> into KISS mode or dialing a modem.  There is also a "tip" command
> which can be used to access a dumb terminal mode using one of the
> asy interfaces.

I guess I am involved in religious OSI layer discussions! Functionally,
the NOS ttylink is an application/presentation layer interface which provides
a "chat" link between two peer users. The present NOS implementation is for
the port 87 transport layer socket to be directed to a keyboard/crt/bios
presentation/application layer user interface.

The instruments in question (ranging from GPS receivers down to TAPR's
METCON board) all have a presentation layer functionality designed for
communications with dumb terminals via a (layer 1) RS-232 spigot.

So, to be very specific, what I am seeking is a way to achieve this same
functionality via TCP/IP. One simple solution would seem to be to patch
the present NOS ttylink I/O to a COM# port in lieu of the keyboard/crt/bios
interface.

OK -- did that establish the POPCORN (Proper OSI Politically Correct
Officious Religious Nuances) for my original question?

Tom





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Created 2004-11-12. Last modified 2004-11-12. Your visit 2020-10-31 16:19.12. Page created in 0.0478 sec.
 
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