> I'm coming to time-nuts because I remember that at least one member had a
> very large number of adapters on one computer, so I'm hoping to find some
> help. I don't generally seem to have trouble with other USB devices, just
> the serial adapters.

Cash,

True, it's somewhat off-topic but a lot of us collect data from instruments and 
so the issue of serial ports and USB comes up from time to time. I have run up 
to 40 serial ports on a Windows laptop using a combination of USB 7-port hubs 
and EdgePort 8-1 serial/USB adapters. It can work perfectly. Some personal 
comments:

- Use FTDI serial/USB adapters. They are very solid on Windows. Avoid SI Labs 
and Prolific adapters. My favorites these days come from Sparkfun and Adafruit 
(serial, 3.3/5 volt) and Parallax (serial, true RS232). Avoid the fake-FTDI 
adapters you see on eBay.

- Use Digi (Inside Out Networks) Edgeport serial/USB adapters if you want 4-1 
or 8-1 or even 16-1 serial ports. I've never had trouble with Edgeport 
software. These are higher priced per box but lower on a per-port basis. They 
are available and cheap on eBay, since DA9 (DB9) serial ports have fallen out 
of fashion.

- Both FTDI and Edgeport include excellent configuration utilities. For 
example, you can delete COM ports or change COM port numbers on the fly. Some 
programs won't let you use a large com port number. In a few seconds you can 
redefine a FTDI or Edgeport adapter to be COM2 or COM3, etc.

- By default the FTDI and Edgeport serial/USB adapters will retain their COM 
port number(s), which is handy most of the time. For example, I have an 
Edgeport/8 with #2 written on it. Every time I plug it in, I COM21 to COM28 
show up. Similar ones have labels #3 and #4, etc. So I always have serial ports 
if I need them.

- If you play with serial ports a lot it's nice to know what the port numbers 
are when you plug adapters in and out. Under http://leapsecond.com/tools/ see 
the coms.exe (coms.c) tool which displays and monitors for changes in the list 
of com ports. ^C to exit. 

- The web also has lots of advice on how to clean up unused COM ports on 
Windows. Personally I tend not to bother, because the config utilities allow 
you to change any port you want to use.

- The web has lots of good (and bad) advice to avoid the serial ball mouse 
problem should you ever run into that.

- If you want Windows serial logging and timestamp software contact me off-list.

Thanks,
/tvb

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