conflict with two serial to USB devices

**KShoes** · 09-13-2008, 10:46 PM

I have two serial to USB devices that don't want to play nice with each other all the time. The first is my GPS receiver and second is the OBDII scanner. On initial setup both are detected and both operate. It may take 1 or maybe a dozen reboots for the conflict to occur, when it happens the GPS is always the one that disappears. Is there a way to lock these two devices on their respective comm port?

**sirnephilim** · 09-13-2008, 11:02 PM

Friend of mine had the same problem with a GPS and a generic USB-to-Serial adaptor (he did A/V installs - all the programmable stuff uses native serial for some idiotic reason) where one would occasionally drop out. For him it was always the adaptor.

The solution was to boot with only one (or neither) plugged in, and then plug it in later. Dunno if that's possible in your case, but it should work.

Possibly, removing one or the other's driver, unplugging the unit, rebooting, then plugging the unit in and reinstalling the driver MIGHT work. That's what they kept telling my friend to do, anyway.

**FPeter** · 09-14-2008, 09:13 AM

are you tried to change their COM-number? go to its properties panel in device manager > port setting > special. you can select the free numbers from 1 to 256, but i always had problem with my gps and serial adaptor if they went to 1x-2x or above automatically... choose the smallest possible number for them, this might help!

**KShoes** · 09-14-2008, 08:31 PM

Thanks for the replies - indeed leaving the OBD unhooked until after the machine boots does solve the issue - that is until I forget. I have them set on comm 2 for the OBD and comm 5 for the GPS. When the problem happens the GPS disappears with no amount or combination of plugging / unplugging and rebooting will get it back until I uninstall the OBD by setting nonpresent devices to show and uninstalling from there.

**fixerofallthing** · 09-14-2008, 08:59 PM

What about trying different drivers. I use 3 different devices that all came with their own drivers and I ditched them all for the Prolific drivers and they all get along fine now. My GPS used to disappear as well.

**FPeter** · 09-15-2008, 12:04 AM

Originally Posted by fixerofallthing

What about trying different drivers. I use 3 different devices that all came with their own drivers and I ditched them all for the Prolific drivers and they all get along fine now. My GPS used to disappear as well.

its a good idea, the most common chipsets are Prolific PL2303 and FTDI FT232

if its an another type and you cant find the latest driver (from chipset vendor, not the product's support page! - its very old in most cases...), write here the VID_ and PID_ number, and we will try to find the proper driver...

**sirnephilim** · 09-15-2008, 01:19 AM

Put bluntly, USB-to-serial is a crock in which some of us are doomed to stew. Every time I hear the words "virtual COM port" I know beyond a doubt that something's going to screw up eventually.

**KShoes** · 09-15-2008, 05:07 PM

Originally Posted by FPeter

its a good idea, the most common chipsets are Prolific PL2303 and FTDI FT232

if its an another type and you cant find the latest driver (from chipset vendor, not the product's support page! - its very old in most cases...), write here the VID_ and PID_ number, and we will try to find the proper driver...

Thanks - the GPS is indeed the Prolific driver. I'll see if I can make them both happy with that driver. The other important detail I left out (ashamed) the OBD is the cheapest pile of junk I could find. That fact is sometimes asking for trouble, thanks again all.

**FPeter** · 09-15-2008, 06:25 PM

Originally Posted by KShoes

Thanks - the GPS is indeed the Prolific driver. I'll see if I can make them both happy with that driver. The other important detail I left out (ashamed) the OBD is the cheapest pile of junk I could find. That fact is sometimes asking for trouble, thanks again all.

this is not a problem if works, the chipset is a general one inside, not custom-made noname thing...