Now you can proceed to check out the system specific guides on how to interface different vintage computers and devices with VModem. Once you are done, return back to this guide!
Make sure vmodem.sh is running on the Raspberry Pi first before attempting connection!
After you have verified that the VModem works properly on the console, and you have tested that you are able to connect to your network, you can make VModem run automatically as a background process after the Raspberry Pi is powered on. It will run as a background process so you won't see it's output, so it's highly recommended to thoroughly test the script first.
exit 0. Now add the following lines ABOVE it.
# Start serial port and simulate a modem cd /boot/vmodem/ /boot/vmodem/vmodem.sh &
Beware the ampersand “&” at the end of the line. Without it, the boot process may not complete correctly (or at all).
Functional Hayes commands:
Cannot communicate on serial terminal with the vmodem script
After running the Virtual Modem script on the Raspberry Pi, and connecting it to your computer via the USB-to-Serial adapter and a null modem cable, you should be able to fire up a simple serial terminal on the computer and issue a few Hayes commands to ensure connectivity. Hayes commands are a common way to communicate with Modems, and by typing AT and pressing enter in the terminal, you should see an “OK” response. The vmodem script also recognizes other commands, such as HELP which should provide a short list of recognized commands). If you receive a garbled response after typing AT or HELP, your serial speed settings may not be the same on both ends. Make sure you have adjusted the communication speed to match. If you receive no response whatsoever, you might have a problem with the USB-to-Serial adapter or you may be using an older UART on your computer (see section 2 for more on this). If you're still unable to communicate with the VModem script, feel free to join our Discord channel (see bottom of page for link) for further support. Simple tutorials can only go so far… :)
After dialing in, system is disconnected immediately
Make sure you are using the latest version of the Virtual Modem script. An early version had an issue where the serial connection would be cut before the network connection was established. Also, be sure to make sure your serial baud settings are correct, and they match the virtual modem script. Finally, try turning off Flow Control from the Modem Settings under Advanced Settings.
After dialing in, system reports connected, but no network is available
Make sure you have updated the network device in vmodem.sh to reflect the correct network interface. By default it is eth0. If you are using Raspberry on WIFI, you may need to change this to wlan0.