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Modem/Serial Comm. Problem

G. Ainscow

Joined: Oct 31, 2004
Posts: 9

I've spent two full days trying to find an answer to this question, without
any luck.

When I send an AT command to my modem it just echo's it right back at me,
instead of sending some form of acknowledgement, such as an OK response

Of course, this means it doesn't respond correctly to dialling commands
either (AT Dnnnnnnn).

The problem is this: BlackBox works, as well as another sample application I
have -- just not <my> code (typical).

Any ideas as to why this is happening? Could it be that my sending and
receiving is not done in separate threads?

Some info:
OS: Windows 2000
JDK: 1.5.0
Modem: 3Com U.S. Robotics 56K Faxmodem

My code follows: (Test & _SerialPort)

Note: I'm using RXTX for communication, same/similar API to the sun implementation.

If you have any other working sample code for serial/modem i/o, please send
it my way.


Mike Gershman
Ranch Hand

Joined: Mar 13, 2004
Posts: 1272
Try ATDT xxxxxxxxxx

Mike Gershman
SCJP 1.4, SCWCD in process
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

Hi Glen,

Welcome to JavaRanch!

First, a bit of business: you may not have read our naming policy on the way in. It reqiures that you use a full, real (sounding) first and last name for your display name. Initials aren't enough. You can change your display name here. Thanks.

Now, as to your question: this really belongs in our Other Java APIs forum. I'm going to move it there for you.

[Jess in Action][AskingGoodQuestions]
I agree. Here's the link:
subject: Modem/Serial Comm. Problem
It's not a secret anymore!