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RS232-Quickstart-Guide

Table of Contents

Overview

FujiNet RS232 currently targets MS-DOS (PC Compatible) systems over a serial port. Support for other serial devices will likely come in the future.

Requirements

In addition to a MS-DOS (PC Compatible) computer, you also need:

  • USB-C 5V power source (1A or higher recommended)
  • FAT32 formatted SD card with fnconfig.ini file containing your local WiFi login credentials and serial baud rate
  • Method to copy the FUJINET.SYS driver onto your MS-DOS computer

Hardware

Description

The RS232 hardware is different than previous FujiNets in that it uses the new ESP32-S3 chipset instead of the usual (older) ESP32. This newer silicon is similar in function to the original ESP32 with some beneficial upgrades.

Power

The FujiNet for RS-232 requires a standard 5 volt USB-C power source. It is recommended to use a supply that provides at least 1 AMP of power. Be sure to provide power to the FujiNet before powering up your computer.

Note: As with other FujiNets, there is no power light. The two LEDs indicate WiFi link and serial activity.

Software

Driver

A DOS driver is required to use FujiNet which can be found in the fujinet-rs232 repository Releases. The most recent version of the driver will be at the top of the page. From the Releases page, expand the "Assets" link and download the .sys file. (currently named 'fujinet-4bb4134.sys'). Rename the driver file to 'fujinet.sys' and copy it to your system's boot disk/drive. Add a new line to your CONFIG.SYS to load the driver:

DEVICE=FUJINET.SYS

FUJI_PORT defaults to 1 (for serial COM port 1) but can be changed to the number of the corresponding serial port FujiNet is connected to (ie, 2 or 3).

FUJI_BPS can be changed to the highest baud rate compatible for your machine. The default speed is 115200. If you find that your computer hangs when accessing FujiNet mounted drives, try lowering your baud rate. (For instance, try 57600, then 38400, all the way down to 9600.) If you want to change it to something else, it must be set in both CONFIG.SYS and in FujiNet's fnconfig.ini file as shown below:

Add FUJI_BPS and/or FUJI_PORT to CONFIG.SYS:

DEVICE=FUJINET.SYS FUJI_BPS=9600 FUJI_PORT=2

Update fnconfig.ini:

[RS232]
baud=9600

Apps

Some FujiNet enabled apps are available in the same fujinet-rs232 respository in source code form. These can be built with the Open Watcom compiler or precompiled versions are available on apps.irata.online tnfs server.

Connecting to Wifi

As of September 1, 2025 the CONFIG app (mounted by default when FujiNet starts) does not work completely and thus you cannot setup wifi or mount disks from the Host computer. Until CONFIG is working, you can manually edit the fnconfig.ini file on SD card with your wifi credentials to get the FujiNet connected.

Once connected, point your browser to fujinet.local or the IP address acquired by the FujiNet and you will be presented with a web interface for mounting disks.

Setup Procedure

  1. Download the sample fnconfig.ini file, save it on your FAT32 Micro SD card, and insert the card into your RS232 FujiNet. The fnconfig.ini file should contain: a. Your local WiFi username and password, b. Baud rate for your serial connection
  2. Before connecting your RS232 FujiNet to a computer, plug in the USB-C power supply. If your WiFi credentials are correct, you will see the white WiFi connect LED begin to glow. This confirms that your RS232 FujiNet is powered and connected to WiFi.
  3. Using a "modern" computer, browse to fujinet.local. You should now see the configuration page generated by your RS232 FujiNet.
  4. Use this configuration page to specify your drive mounts. Be sure to click the link labeled "Mount All".
  5. Your FujiNet will remember these mounts as long as it remains powered by the USB-C supply.
  6. Load the FUJINET.SYS driver onto your MS-DOS computer and edit CONFIG.SYS to load the driver. Be sure to specify the proper COM port and the same baud rate entered in fnconfig.ini on the SD card.
  7. Boot your computer. If the FujiNet driver is able to connect, it will report the firmware version for your FujiNet Device.
  8. Drive letters should now be assigned to all drives mounted by the FujiNet.

Common Troubleshooting Considerations

  • Typo in the WIFI name and password in the fnconfig.ini file on the SD card
  • SD card not formatted as FAT32
  • Baud rate not set the same in fnconfig.ini and config.sys
  • Baud rate too high for your computer’s UART
  • Incorrect COM port specified in config.sys
  • COM port not enabled in computer’s BIOS

Wiki content is mirrored from the FujiNet Github Wiki