InfoStructure Technical Support
Technical Support for Finding Your Modem
Finding where your modem can be interesting sometimes because of how it is
configured. Two of the more common ways to find your modem are outlined below:
- One way that I like to find a modem is by using a terminal
program. I like to use Terminal in Windows 3.1 and Windows for
Workgroups 3.11. With this program, I can test each Communications port to
see if there is a modem attached to it. Here is how I do that:
- Find your Terminal program in the
Accessories group in the Program Manager.
- After double clicking on the icon to run the program, it
may come up with an error like this:
"The seleced COM port is either
not supported or is being used by another device. Select another
From here, hit the OK button. If the Communications is open
then skip to #3, else continue to step #2.
- Go to the Settings menu and select Communications
- In the Communications window, about half way down
on the right side, there is a small box with the title Connector.
This box is a small scroll box with a list of the Com ports with None on the
top. What we need to do from here is select each Com port and do a test on
each and which every passes, that is the modem port.
- Select the next available Com Port (the first time, this would be Com 1).
- If an error occurs like the one in #1, then hit OK and go back to step
#5, else continue.
- The screen should be a blank Terminal window with a cursor blinking
in the upper left corner.
- Try to type "AT" (without the quotes) and hit RETURN.
- If nothing happens, or strange characters appear, go back to Step #5.
- If the modem responds with an 'OK', then the Com port that you are on, is
the port where the modem is. Remember that number, or if necessary check the
Communications under Settings again to see what Com Port it is set at.
- Now you can exit the program. It will ask if you want to save the setting,
here you can save them if you like but these are only the settings for Terminal so I
always cancel here.
- And now you can set the proper Com Port in TCP Net Dialler.
- Another way to check is through DOS.
NOTE:This is only pertinent to modems of
14,400 or faster. If you do not have a modem that contains the 16550 UART
chip, this screen will at least show you the 'live' Com Ports to check in a communications program like
- Run the program MSD (Microsoft Diagnostics).
- This will bring up the diagnostic screen and we are looking for Com Ports
so choose the Com Ports (You will also notice how many Com Ports are available on your
- In columns, it will list the Com Ports and onlyl the Com Ports information
in the columns are 'live' so the modem isn't in one of the Com Ports that list no information.
- Check the UART Chip Used row for a Com Port that has a 16550,
16550A, or 16550AF. This would be the chip that is has been detected from the modem.
- If there is only one with a 16550 chip, then that should be the modem and you
can set that Com Port in TCP Net Dialler.
- If there is more than one Com Port with a 16550 chip, then you can narrow it
down and test the ports with the 16550 chips in the terminal as shown above.
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