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Nick Trolley

Windows 7 Unlimate and USB-to-COMM port numbering

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I'm not sure if this topic has been posted about in the form before - i tried to google search it and all the returns i found seemed to reference windows XP - Im' running windows 7 ultimate 64 bit service pack 1 the issue is that when i currently plug in my USB to serial converter cable the system wants to auto assign it to Comm 14 since thats the next free comm port i have - im wondering how do i go into my system and release say comm ports 3-4 so that when i need my usb -to -serial unit it can be put on those comm numbers? the problem is im using directsoft 4 from automation direct and the comm link software only goes up to comm 9...... i could upgrade to direct soft 5 which supports up to comm 99 but i'd rather not if i don't have to, plus im sure id have this issue on some other plc programming software too..... i have a feeling i have to use hardware manager in my control panel but im not sure how to change the comm numbering or release ports no longer in use - and if i do will i screw anything up?

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Go into Device Manager, select the port, right click, change settings to a lower COM port number.

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I have done that - the lower port numbers were listed as being in use - when i changed the port number to a one listed as in use i got a warning saying that this could cause the device to become unuseable? also when i removed the device and pluged it back in the computer put it back on port 14 - as if it still viewed the lower ports as being in use even though i had removed all of the "in use" message status?

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What kind of converter are you using? I'm using a Keyspan model on XP. I have used it under 7 also, but I don't remember having this problem. You should still be able to go to device manager and find the port that the adapter is connected to. Under the settings for that port, you would redirect the adapter to a different port and reboot if it's already "in use". Mine seems to "remember" its setting (COM1 right now) and grab that port first, leaving other devices to get other ports. Once the adapter is installed and running on a particular port, it tends to default to that one until it is changed. Remember, if the port you're changing to is "in use", you'll probably need to reboot before the change sticks. Does device manager tell you which device is using the COM port number you want to use? It seems odd to me that you would have that many COM ports configured. Another option is to delete all of the COM ports and reboot your computer. Windows will find the COM ports that are actually present and reinstall the driver automatically. Incidentally, this is a handy way to get rid of the Allen Bradley PIC module driver.

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I've managed to get COM4 through COM10 COM11 assigned between a USB/serial adapter and a DL3500 USB/DH+ converter. These are unserialized devices, which means Windows assigns a unique COM port each time a device uses a different USB connection. With two devices, four USB ports on the laptop and a four port hub, the combinations start to add up. If a device is seriallized, the driver only assigns the COM port once. Anytime the same device is reconnected, regardless of the USB port, the driver recognizes it and recalls the existing COM port assignment. I just learned this a few weeks ago, after noticing that the COM port did not change on a customer's new laptop and USB/serial adapter. That said, the only sure way to free up COM ports may be to plug in each device and go into Device Manager and remove the driver. At least, the ATEN driver does not appear in Add/Remove programs and shows in Device Manager only when the device is plugged in. Mike

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This is one of the reasons I strongly recommend the Keyspan HS-19 USB/RS232 converter. Not only is it a "serialized" device so it only ever gets one enumerated COM port, but also the small Windows utility that comes with it allows you to change the COM port number easily. The extra twenty bucks to get the Keyspan HS-19 is absolutely worth it.

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What he said ;) If you have a lot of unused COM ports listed under device manager, just delete them and reboot. Windows should automatically find any devices that need them and re-enumerate the ports.

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Many of those COM ports are possibly placeholders for things like VMware or Blackberry Desktop or other packages like that. My PC has a real COM1, the modem is COM4, and I set up for COM2 on the USB without issue. Keep in mind also just because it says it's in use doesn't mean it's attached at that point. It may be reserved by a driver for a device which is not currently connected, and thus not using it. When I set up my USB-Serial on a different USB port, it tried to give it a different COM number. I changed it to the same one as the first port, and it warned me that it was already in use. Since I only have one adapter, there can't be a conflict as I can only plug it into one USB port at a time. So I clicked continue and all is well...

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can you post screenshot of your ports in device manager? we need to see what is going on. btw. i used to have similar problem. it turned out that installer for a blue tooth product made some 20 blue tooth RS232 ports. ...how convenient....

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