Why is Minicom Not Recognizing My USB Modem?

Introduction

Minicom is a popular terminal emulator often used for modem and serial port communication in Linux. However, it’s not uncommon to encounter a situation where Minicom does not recognize a USB modem. This article will delve into why this happens and offer solutions to fix this issue.

Understanding the Problem

When you try to run Minicom, you might encounter an error message stating, “minicom: cannot open /dev/modem: no such file or directory”. This error arises because Minicom is trying to open the device /dev/modem, which is not where your modem is located.

To confirm the location of your modem, you can run the command wvdialconf /etc/wvdial.conf. This command scans your system for modems and writes a configuration file. If it shows that the modem is found on /dev/ttyUSB0, it means that your modem is not on the /dev/modem location that Minicom is trying to access.

Solutions

Changing the Minicom Settings

The first solution is to change the device in the Minicom settings to /dev/ttyUSB0. You can do this by running the command minicom -s to open the setup menu. Navigate to “Serial port setup” and change the Serial Device to /dev/ttyUSB0.

Running Minicom with a Specific Device

Alternatively, you can run Minicom with the command minicom -D /dev/ttyUSB0. The -D parameter specifies the device to use, in this case, /dev/ttyUSB0.

Creating a Udev Rule

Another solution is to create a udev rule that automatically creates a symlink for the modem. This can be done by creating a file named /etc/udev/rules.d/95-usb-modem.rules and adding the following rule:

SUBSYSTEM=="tty", ATTRS{idVendor}=="12d0", ATTRS{idProduct}=="1001", SYMLINK+="modem"

In the above rule, replace the idVendor and idProduct values with the appropriate values for your modem. You can find these values using the command lsusb. This command lists USB devices connected to your system.

Creating a Symbolic Link

In some cases, you might need to link /dev/modem to the serial port device. For example, if your serial port device is /dev/ttyS0, you can create a symbolic link using the command ln -s /dev/ttyS0 /dev/modem. The ln -s command creates a symbolic link between the two specified locations.

Conclusion

The main issue when Minicom does not recognize a USB modem is that it’s trying to open the wrong device (/dev/modem) instead of the actual device where your modem is located (/dev/ttyUSB0). By changing the device in Minicom settings or using the correct device in the command, you can resolve the issue.

Remember, it’s crucial to use the correct device location when working with terminal emulators like Minicom. The solutions provided in this article should help you navigate and resolve such issues effectively.

SUBSYSTEM=="tty", ATTRS{idVendor}=="12d0", ATTRS{idProduct}=="1001", SYMLINK+="modem"