# Unable to hangup modem via psuedo-TTY



## ecables (Dec 16, 2009)

Sorry, it's me again with this annoying modem/psuedo-TTY configuration.

I am currently utilizing a modem represented by a psuedo-TTY, which is physically attached to a serial port on a network connected Lantronix terminal server.  

I have been able to represent the modem using either Conserv or Socat, essentially establishing a raw TCP connection to the terminal server, and representing that TCP stream via a local pseudo-TTY (for example: /usr/local/socat/dev/modem -> /dev/pts/#)

I can successfully attach to the modem using Minicom, and even dial-out & connect to remote modems.  Unfortunately that's where my success ends, and my current problem is the inability to disconnect the modem once it has dialed out.  When I issue a "hangup" request in Minicom it simply does not hangup, and barring power cycling the modem, or disconnecting it from the remote side manually, I am unable to send the proper "hangup" signal to the modem.

I'm sure there's a fundamental reason why this isn't working, such as the signal getting lost in the TCP/IP -> serial conversion, but I have yet to find it.

Has anyone gotten this kind of setup to work?


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## ecables (Dec 16, 2009)

I found a solution to this after scrounging through minicom().



> P - Drop DTR time
> If you set this to 0, minicom hangs up by sending a Hayes-type hangup sequence. If you specify a non-zero value, the hangup will be done by dropping the DTR line. The value tells in seconds how long DTR will be kept down.



I set this to 0, default was 1, and instead of dropping DTR to a modem that wasn't physically connected, it now issues '+++' then 'ATH', which works great.


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