Operating Systems > Linux and UNIX

Serial Port Modem is SLOW.. how can i fix?

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Calum:
well, a guy from my LUG list said:  
quote:  Calum,
The serial link between the modem and serial port probably won't work reliabliy above 115000.
Since you get connected everything else must be OK.
Have a look in /var/log/messages to see what chat messages are there after you get logged on.
Try tail /var/log/messages to see the last few lines. I think tail -n 100 /var/log/messages shows you the last 100 lines.

Reduce the serial port speed and see what happens.
Regards,

--- End quote ---
will try and will post results here, for others' reference.

voidmain:
That's pretty much what I said in the last couple of messages other than you should try to get it to work at 115,200 if possible. With a 56k modem you will be limiting the troughput if you don't. But like I said you can't always get it to work at that high of a port speed. I have no experience with that brand of modem but it appears to have an AT command set. You might experiment with turning on/off error correcting protocols in your init string as I said before (I see Red Hat also has checkboxes in the modem properies for this).

On another note, most external modems I have used with great success are USR modems. But I have had a few Zoom modems that worked just as good. Look through your modem manual for a command set and modify your init string accordingly. Sorry I haven't been able to give you any more to go on...

Calum:
i took your advice and now it seems my serial modem is working to full potential! thank you very much for your advice!

still, i am interested in these initialisation strings... maybe i will indeed read up on them.

voidmain:
If it's working fine I wouldn't bother. Except for a couple of tricks I usually add to the init string for speeding up the dialing and turning off the sound:

M0 S11=50

The "M0" turns the speaker off and the "S11=50" sets the dialing speed up to 50 milliseconds between numbers (very fast, and about the fastest you can go ). If your modem has Hayes compatible AT command set these should work. Your manual should list all of the "AT" commands.

Calum:
yup, i think it's hayes compatible, but i think i'll leave the speakers on since i like to be paranoid about having my modem owned and used to dial high price numbers in thailand without my knowledge!  :D

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