TTYLINK, OSI layers and POPCORN
- To: email@example.com
- Subject: TTYLINK, OSI layers and POPCORN
- From: firstname.lastname@example.org (Tom Clark -- W3IWI)
- Date: Wed, 08 Jan 92 19:28:02 UTC
> >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
> 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
OK -- did that establish the POPCORN (Proper OSI Politically Correct
Officious Religious Nuances) for my original question?