[RTTY] USB adapter Interface

[Richard Ferch]

Bill,

The "no output" from your test using COM13 directly in MMTTY indicates 
that your USB-to-serial adapter does not support the 45 baud speed you 
need for RTTY. You will almost certainly have to use EXTFSK. The trick 
is to ensure that Windows assigns a port number that EXTFSK can use 
(i.e. 1-8) to the driver for your USB-to-serial adapter.

You said:

> The USB port I am using is comm 3. Using the adapter, it 
> will make comm 3 into comm 13.

It's not quite clear to me what you mean by this, but my guess is 
something like this: "Since my computer only has serial ports COM1 and 
COM2 occupied by real devices on the motherboard, I would have expected 
the USB-to-serial adapter to be on COM3. However, Windows has assigned 
port COM13 to the adapter."

If there truly are no other real or simulated serial devices in your 
computer, you can override the choice made by Windows and assign another 
port number to the device.

In Windows XP, you can do this as follows:

Open the Control Panel and select System.

Select the Hardware tab and click on the Device Manager button in the 
upper part of the window.

In the list of hardware device types listed by Device Manager, click on 
the + sign next to "Ports (COM & LPT)". You will see a list, including 
entries like "Communications Port (COM1)", "Communications Port (COM2)" 
and "ECP Printer Port (LPT1)" - these are the real serial and parallel 
ports installed on your motherboard - and at least one entry such as 
"USB Serial Port (COM13)" or "Prolific USB-to-Serial Comm Port (COM13)" 
or something else along those lines (depending on which chipset and 
driver the adapter uses). If you are using software (like the microHam 
Router or LP_Bridge) that creates virtual serial ports, you may also see 
entries such as "ELTIMA Virtual Serial Port (COM6)".

If you have other serial hardware devices (including USB-to-serial 
adapters such as the one inside the WinKey USB), you will not be able to 
use port numbers assigned to them. Likewise, if you have software that 
creates virtual serial ports, you may not be able to use any of the port 
numbers that this software has assigned, or at least not without first 
reassigning one or more of the virtual ports to a new number. However, 
there is a good chance that there is at least one port number in the 
range 1-8 that is not used in your system, in which case you can change 
the port number assigned by Windows to your USB-to-serial adapter from 
COM13 to this unused port number.

Right-click on the entry that ends in "...(COM13)". In the pop-up menu, 
select Properties. Select the Port Settings tab and click on the 
Advanced... button. At the top of the window that appears there will be 
a listbox called "COM Port Number:". If you click on the down arrow at 
the right end of this listbox, you will get a list of port numbers 
(1-256) from which you can choose a new one. Some will be marked as "(in 
use)" and others will not.

Ideally, there will be at least one number in the range 1-8 that is not 
in use. If so, just select one. That should enable you to find and use 
this adapter from within EXTFSK.

If you find that Windows is claiming that all of the port numbers in the 
range 1-8 are in use, you may be a victim of Windows' long memory. The 
"(in use)" flag may actually be indicating that this port number was 
used once in the past, rather than that it is being used now. If this is 
the case, it may be safe to use the number despite the "(in use)" 
marker. Windows will complain when you try to select it, but it will 
allow you to override the complaint.

Using this technique, you may be able to get Windows to assign a low 
enough number to your adapter so that you can use it with EXTFSK.

There is one other trick to this. In MMTTY, after you select EXTFSK as 
your port number for PTT & FSK under the TX tab in the MMTTY setup 
window, and after you then select one of the two COM-TxD(FSK) choices as 
Tx Port under the Misc tab, a button labelled USB Port will appear. 
Click on this button and select the "C. Limiting Speed" option to ensure 
that MMTTY's PTT timing is correct.

Good luck!

73,
Rich VE3KI