Serial Port Woes

[zestril5]

I purchased a new laptop for a friend and later realized it had no external serial port connection. Unfortunately he has a device that only works with a serial port and the port can only be com1, 2, 3 or 4. (5 is not an option)

I purchased a USB to Serial port adaptor and installed it on the XP pro system with an xp pro driver. It installed as com5. When I tried to change the com port the system shows com3 and 4 are in use. Com1 and 2 are available. I tried changing com5 to 1 and then to 2 but the results were the same. Although the system show the adaptor on com1 or on com2 the device can't be found.

If I remember correctly com1 is the same as 3 and com2 is the same as 4 so I wasn't surprised that the device didn't work. What I don't know is what is using com3 and 4. I believe it may be the PCMCIA ports. If this is the case, can I disable one of the PCMCIA ports to free up a com port?

I really need some ideas to resolve this problem. Thanks

 

[Bobg1]

An internal modem would be using a com port.
You can also check com port settings from bios and see how things are set there.
Your statment about ports being the same is not quite true.
Com 1 and 3 by default used the same irq, as did com 2 and 4. There are ways around that. The ports them selves are not the same.

 

[zestril5]

I did disable the internal modem but it didn't release either com port.
I understand about the different irq settings but thought it might be easier to stop using the com port altogether then fooling around with all the settings.
Thanks for your response.

I'm going to go try disabling the PCMCIA ports and see what I get. I'll post back when I return.

 

[bcastner]

The PCMCIA adaptors seem unlikely as the issue.

First, check the BIOS settings to see any legacy support for serial devices exists.

Second, in Device Manager you can try disabling, or even uninstalling the driver support for ports 1-4.

Although if XP is permitting without complaint the re-assignment of the USB device to lower ports than #5, but the device is not found, it is suggestive of problems with the USB driver itself. Some versions will only work with a COM 5 assignment.

 

[zestril5]

I got the com port issue resolved.
The card that was going into the PCMCIA slot (not the slot itself) was using a com port. The card had been installed in the lower PCMCIA slot originally and used com 4. At some other time the card was put into the top slot and installed itself again this time using com 3.
I uninstalled the card altogether and reinstalled it in only one PCMCIA slot. This freed com 3. I then uninstalled the serial adaptor and reinstalled it. It installed itself on com 3.
Unfortunately the serial device I'm trying to get to work still doesn't work but that's another problem that I'll take up with the manufacturer.
Thanks for the help.