OS/2, eCS & ArcaOS - Technical > Setup & Installation

USB to Serial adapter setup

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Doug Clark:
I have a serial device that I have working when connected to a real serial port.

I would now like to get it working through a USB to Serial adapter.  The one that I am using is a Belkin fsu116 hub thingy - which plugs into usb and provides 2 serial, 1 parallel and 2 usb ports.  It is shown as working with os/2 in the wiki.

Do I need to add something to my CONFIG.SYS to get the ports working?  Can I assign a comm port number to a specific port on the belkin?

Is there documentation somewhere that describes how you setup usb-serial adapters?


Dave Yeo:
IIRC, you need usbcom.sys installed  as a device (DEVICE=x:\os2\boot\USBCOM.SYS /V), I had it after USBKBD.SYS in config.sys with /V for verbose. Default should capture the 1st free serial port.
I thought I had some documentation on it but can't find it right now, mostly about setting up the port. Install and play with the mode command to see if it works. There are others who should know more.

Martin Iturbide:
Hi Doug

I found this for the moment:

Is it USBSer.sys also needed?

I was wondering which kind of devices you want to test on the USB Serial port that you have. Are you trying to access to the console of a device with a terminal application?

Even that I got my hands in some USB-to-Serial adapters, I never found out a device I can use easily to confirm the USB-To-Serial port is working.  Was USBCOM.SYS only meant from modems? Was some other devices like serial mouse, serial cable, etc that may work ?

Please let me know your progress, model number of the device, so I can add that device on the wiki.


Doug Clark:

thanks for the usbcom.sys tip.  That got me started, at least.  I added the following two lines to my CONFIG.SYS


and the messages on boot up appear to say the driver is loaded for each com port.

But when I enter MODE COM2  or MODE COM3 I get the message
The system cannot find the device specified.

I have one physical COM port in the motherboard, which is used normally used
by my ACECAD driver.  The CONFIG.SYS lines for that driver are


If I put  COM.SYS in my config.sys with the ACECAD driver I get an error message when it tries to load COM.SYS.

If I take out the ACECAD  stuff out of CONFIG.SYS   COM.SYS loads and I can use COM1 - and MODE COM1 works correctly.


The device is an IBM 6094-20 Lighted Program Function Keyboard (LPFK) which needs a serial connection.
You can see it in action, along with a 6094-10 Dials device at


I ported the source for a a Linux "driver"  (actually just an interface to the serial port for this device with a test program) to OS/2 - but to do that I had to remove the ACECAD driver and connect the LPFK to the real serial port on my machine.  I am now trying to get it to work through a USB - > serial adapter.

Martin Iturbide:

Just for the fun of it I took out a "Prolific USB 2.0 to COM" (HardwareID: 067b:2303) device to try it on my ArcaOS VM.
- Added "DEVICE=C:\os2\boot\USBCOM.SYS /V" after USBKBD.
- Configured the VirtualBox VM to enable COM1
- Rebooted

With the device disconnected I run "MODE COM1" and got
 SYS0021: The drive is not ready.

I plugged the adapter, without any serial device attached.
Mounted in VirtualBox the "Prolific USB 2.0 to COM" USB device, and run again "MODE COM1" I got:

--- Quote ---baud     = 9600                   parity   = NONE
databits = 8                      stopbits = 1
TO       = OFF                    XON      = OFF
IDSR     = OFF                    ODSR     = OFF
OCTS     = OFF                    DTR      = ON
RTS      = ON                     BUFFER   = N/A
--- End quote ---

So, I guess the device is being recognized in some way. But I don't have any serial device at hand to keep testing.



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