Re: flexfax: How best use multiple modems?

[Leslie Mikesell <les@Mcs.Net>]

>     
>     > Modems connected to network servers will not work reliable with
>     > HylaFAX because you can't control the time over a TCP/IP link
>     > to match the T.30 timer demands.
>     > 
>     > 
>     Can we use modems that support class 2 Rockwell type command set over 
>     the TCP/IP network instead of connecting them to the serial devices? 
>     Would they handle the T.30 timer demands internally?
> 
> The modem will handle the timer correctly (if it does handle
> them correctly et all) but you can't make sure to pump the
> data or AT-cmds to the modem (or read answers from the modem)
> in the timer intervalls.

TCP doesn't guarantee the timing but an ethernet has to be pretty badly
loaded to impose significant delays handling something like a 19200 baud
serial stream.  I'd expect this to be possible if both ends do something
reasonable with the delay trying to accumulate characters into packets.
You can control this with TCP_NODELAY on the unix side, but I don't
know if this is tunable on the terminal serve side.  Also, with the
current version of HylaFax you have to go through another program
that maps a pty to the socket which is probably not very efficient.
It might help if HylaFax were able to open a socket directly to
the modem.  

 Les Mikesell
   les@mcs.com