Comm Ports in XP

DoubleT · Dec 5, 2008

I am working on a computer that needs to send information out a USB port to a circuit board that controls access to a building. For reasons I won't list here plugged into the USB port is a usb to serial converter. This USB to Serial converter has a short and it is difficult to keep the link up. I have another USB to Serial converter (a Belkin) that doesn't have a short (green light indicating connection stays on). However, the information will not reach the controller when I am using this converter (same USB port). By the way I have loaded the driver for this USB to Serial converter.

When I look in the application that is sending the data, the selection is set on Serial 232/USB. I looked to see the serial port that is specified and it is "6". Is it possible that when I installed the driver for this Belkin USB to Serial Converter that it assigned it a different serial port. If so, how do I find out which one? (XP Pro OS). I'm thinking if I can tell the app which port to use for the new Belkin converter I will be back in business.

tecknomage · Dec 5, 2008

You need to remember that both Serial Com & USB have line-length limits. That is, the devices must be close enough to not exceed the limits.

I don't think using a USB-to-COM converter uses a COM Port number. This assumes that you use the exact same converter at both ends.

Computer-1 <----> USB_signal <----> Serial_COM_signal <----> USB_signal <----> Computer-2

Note that USB does not have "ports" so that makes port assignment irrelevant. This is assuming you are using a USB connections on both computers.
IF you are using:

Computer-1 <----> USB_signal <----> Serial_COM_signal <----> Computer-2

Again, port assignment is irrelevant. Whatever COM Port you plug into at Computer-2 will be the one, and the Port# should be labeled at the connector.

Did you open Device Manager, Ports tree, and see what it has listed? (see screenshot)

Now if you have a Belkin USB/Serial Converter Utility that was installed with the driver, you should look at that. If you do NOT have such a utility, then the Belkin does not configure anything (no Port assigned).

DoubleT · Dec 5, 2008

Thanks for your reply, Technomage. I believe you are right on the comm port being irrelevant. What I have here is "computer > USB to Serial converter > serial to rj-11 convertor (looks like a phone plug) > phone line cable > circuit board on wall." No, I didn't set this up. This is a local gym that uses this app to control entry access. It has been working for them for over a year and recently quit working (can't get entry key programming to circuit board on wall). When I jiggle the old USB to Serial converter the light lights and signal gets to circuit board. When I put in the new Belkin USB to serial convertor the link light lights up, but nothing ever gets through to circuit board. I have to assume that for whatever odd reason the Belkin USB to Serial converter is incompatible. I have ordered another usb to serial converter (sebring) and am hoping for the best. (I have tested the usb connection and it lights my flash drive every time so it is good).

Chevy · Dec 6, 2008

USB-to-Serial converters are twitchy at best. The chipset and how they manage the conversion greatly affects success.

If at all possible, I prefer to use a serial add-on card (usually very cheap). This allows for a true serial connection and no issues.

Comm Ports in XP

Attachments

Top Contributors this Month

Recommended Communities