USB to COM1 (DB9 serial adapter)? any good?

[Sam Kaan]

I have a laptop on loan to me that has no COM1 nor COM2 ports
(remember those ports used by the old serial mouse?). It just so
happens that I have all kind of hardwares lying around (Single board
computer etc) that requires to be plugged into a serial port db9 (com1
or com2) in order to talk to the PC. I did some research and found
that they do sell an adapter cable that will convert the USB port to a
COM port. My only concerned is whether this works well considering
that USB signal is quite different than the old COM1 and runs also
much higher instead of the old 19.2kbps. Right now I have the laptop
set up to dual boot Win95(DOS) and Win2k. My old softwares for the
SBC runs in Win95 and DOS. So I can always boot into Win95 or even
DOS to run those things. However I am still concerned whether the
USB<-->COM1 adapter will do the job. Has anyone have similar
experiences?

 

[Rene Tschaggelar]

I have a laptop on loan to me that has no COM1 nor COM2 ports
(remember those ports used by the old serial mouse?). It just so
happens that I have all kind of hardwares lying around (Single board
computer etc) that requires to be plugged into a serial port db9 (com1
or com2) in order to talk to the PC. I did some research and found
that they do sell an adapter cable that will convert the USB port to a
COM port. My only concerned is whether this works well considering
that USB signal is quite different than the old COM1 and runs also
much higher instead of the old 19.2kbps. Right now I have the laptop
set up to dual boot Win95(DOS) and Win2k. My old softwares for the
SBC runs in Win95 and DOS. So I can always boot into Win95 or even
DOS to run those things. However I am still concerned whether the
USB<-->COM1 adapter will do the job. Has anyone have similar
experiences?

As far as I know, you need an OS with USB support.
DOS definitely does not support USB.
When the USB works, these USB-Serial devices work.

Rene

 

[scada]

I have a laptop on loan to me that has no COM1 nor COM2 ports
(remember those ports used by the old serial mouse?). It just so
happens that I have all kind of hardwares lying around (Single board
computer etc) that requires to be plugged into a serial port db9 (com1
or com2) in order to talk to the PC. I did some research and found
that they do sell an adapter cable that will convert the USB port to a
COM port. My only concerned is whether this works well considering
that USB signal is quite different than the old COM1 and runs also
much higher instead of the old 19.2kbps. Right now I have the laptop
set up to dual boot Win95(DOS) and Win2k. My old softwares for the
SBC runs in Win95 and DOS. So I can always boot into Win95 or even
DOS to run those things. However I am still concerned whether the
USB<-->COM1 adapter will do the job. Has anyone have similar
experiences?

Do you have a spare card slot? There are many serial port cards (RS232) for
ISA or PCI bus, cheap also.

 

[Tim Auton]

I have a laptop [...]

[snip]
Do you have a spare card slot? There are many serial port cards (RS232) for
ISA or PCI bus, cheap also.

I've not seen a laptop with ISA or PCI slots There may be PCMCIA
ones available but I wouldn't count on it. USB is the way forward if
you've got OS support.


Tim

 

[scada]

I have a laptop [...]

[snip]
Do you have a spare card slot? There are many serial port cards (RS232) for
ISA or PCI bus, cheap also.

I've not seen a laptop with ISA or PCI slots There may be PCMCIA
ones available but I wouldn't count on it.

I read that to quickly, of course a laptop would not have those bus.
www.jameco.com does make a PCMCIA / RS232 card. Part# 164451CF, $120

 

[S.M.Taylor]

No, The USB - serial units are CONVERTERS, not just USB plugs to D
sockets. There is an IC in the connector to do the necessary work. Get
one and use it. They are very useful.

Steve

 

[Joel Kolstad]

I read that to quickly, of course a laptop would not have those bus.
www.jameco.com does make a PCMCIA / RS232 card. Part# 164451CF, $120

And a PCMCIA serial card will show up under DOS at the usual I/O port
locations (3f8/2f8), eh? Cool.

---Joel Kolstad

 

[Roger Hamlett]

I have a laptop on loan to me that has no COM1 nor COM2 ports
(remember those ports used by the old serial mouse?). It just so
happens that I have all kind of hardwares lying around (Single board
computer etc) that requires to be plugged into a serial port db9 (com1
or com2) in order to talk to the PC. I did some research and found
that they do sell an adapter cable that will convert the USB port to a
COM port. My only concerned is whether this works well considering
that USB signal is quite different than the old COM1 and runs also
much higher instead of the old 19.2kbps. Right now I have the laptop
set up to dual boot Win95(DOS) and Win2k. My old softwares for the
SBC runs in Win95 and DOS. So I can always boot into Win95 or even
DOS to run those things. However I am still concerned whether the
USB<-->COM1 adapter will do the job. Has anyone have similar
experiences?

The converters are not 'cables'. They contain a complete microprocessor/USB
interface, which talks to the USB interface, and then retransmits/receives
these on the RS232. There are some that are very fussy, and do not generate
the handshaking signals properly, but generally the latter designs
(especially if they mention being suitable for 'modem interfacing'), work
well.
However they will _only_ work with an OS, that has USB support. W95 does
not. Upgrade this to W98SE (the best of the W9x versions), and the converter
should work fine. W2K will work.
Even the 'best' converters, may give problems, if your applications are
really old fashioned, and try to do 'exotic' things directly with the UART
control registers. The code _emulates_ the standard register addresses, but
there can be latency issues.
As others have said, a PCMCIA com port, is a 'safer' bet.

Best Wishes

 

[Peter Pichler]

And a PCMCIA serial card will show up under DOS at the usual I/O port
locations (3f8/2f8), eh? Cool.

Some of them do. I have just recently seen one on eBay (here in the UK,
I don't know where the OP is from).

 

[Peter Pichler]

I've not seen a laptop with ISA or PCI slots

I have, but it was about 10 years ago. It was a 386 (possibly even 286)
laptop with one spare ISA slot. It belonged to a doctor at the barracks
where I served my national service. He got me to install a joystick card
in there

There may be PCMCIA
ones available but I wouldn't count on it. USB is the way forward if
you've got OS support.

There indeed are PCMCIA cards with COM ports, but (unfortunately, IMO)
USB seems to be much more prevailing nowadays.