Lowering the modem DTR

Posted on 2006-11-08
Medium Priority
Last Modified: 2009-12-16
I have modem which is on leased line mode, i have entered the AT command to use as leased line mode, now i would like to reset the modem, since its in leased mode it doesn't accept any AT commads (AT&F) to reset.
My vendor advice me to sort the serial pin 1 & 20 to reduce the DTR, how can it possible? How to do? any suggestion?
Is there any other way(software) to lower the DTR so that i can run AT commands from the Hyperterminal, according to them i can only apply the AT commads by lowering the DTR.

Question by:joyjohn
  • 2
LVL 93

Accepted Solution

nobus earned 160 total points
ID: 17897122
>>  My vendor advice me to sort the serial pin 1 & 20 to reduce the DTR  <<  then i would do it, since he's the best placed to know.
How to do? with a jumper wire.

Author Comment

ID: 17897312
I have not done before, can you suggest me how to do? with a jumper wire
Is there any link or diagram, if you have could you please provide me.
LVL 93

Expert Comment

ID: 17897559
did he tell you to do it with power off or on?
you have to locate the number 1 and 20 pin and short them.
Can you post a pic of the connector, or inspect it for markings (that usually indicates pin 1)
LVL 57

Assisted Solution

giltjr earned 120 total points
ID: 17899957
There are no external DIP switches?  Typically a modem that can be configured for leased line mode has dip switches so you can reset it by powering it down and up.  At least every one I have dealt with does this.

If toggling DTR resets the modem, then all you should need to do is disconnect and connect the cable between the modem and the device it is talking to.

Now the other possible option is that some modems I have run across will allow you to enter an "escape" code and the modem will start accecpting AT commands again.  The escape code is typically 3 plus signs in a row and then you wait for 3-5 seconds and you get a "OK", you can then start entering AT commands again.

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