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Usb To Serial Troubles


Screed92
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tech question. I've been using a usb to serial adaptor to connect my GPS to the computer. I was using Windows ME and it all worked great. I upgraded to WinXP Home Edition last week, finally gotten around to getting the GPS hooked up and guess what. Mapsource can't find the GPS and GSAk gives me this message:

 

GARMIN: can't init COM3.

 

of course, the usb to serial is setup using com3.

 

I just can't figure out why all this crap don't wanna work together. I never had any problems using any of this stuff with ME, but everything has gone all hinky with XP. I've figured out most of it, but i'm having real trouble with this one. Any help?

 

Thanks

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GARMIN: can't init COM3.

of course, the usb to serial is setup using com3.

 

I just can't figure out why all this crap don't wanna work together.  I never had any problems using any of this stuff with ME, but everything has gone all hinky with XP.  I've figured out most of it, but i'm having real trouble with this one.  Any help?

In all likelyhood you may have to go to the web site of the USB to serial adapter manufacturer and download an XP compatible driver set. I had to do that with mine.

 

When you get the adapter recognized... Power the system off and then plug in the GPS and you should be okay. You may also need to download a specific xp driver for your GPS as well.

 

The XP and ME drivers are so different that I had to do this for every piece of equipment I had.

 

Another thing... XP sometimes does funny Comport assignments.

 

After I upgraded the driver and installed the USB to Serial and plugged it in and got XP to recognize it, I then went to Control Panel, System Manager, Device Manager, Ports and checked to see what port the actual adapter was assigned to... Even though I had only an internal modem in the laptop, XP assigned the USB to Serial adapter to Com4, skipping COM2 and COM3.

 

Once I figured that one out, I configured my map software to COM4 and everything was fine. It was talking again.

 

Oh yes... almost forgot an important aspect of serial adapters... Even though you are using a USB port, the serial port side of the adapter likes to be initialized when you start the computer. In otherwords a cold power on start. It is just an old part of the serial protocol that comes to us as a legacy from DOS. The Power On Self Test, initializes all Serial ports.

 

All that means is you will have the best results with your GPS to turn it on and then to attach it before you turn on the power on the computer and let the POST and operating system initialize the port correctly. Depending on your USB to Serial adapter, you may be able to remove it after a POST initialization has set the port and then re-attach and they may be still talking.

 

This is after you have gotten XP to recongnize the USB to Serial Adapter to begin with... when you are doing that part of the process it is best not to have the GPS attached to the apapter yet. Let XP see one device at a time on that port or it gets a bit confused as it sets the port sequencing and identification up.

 

I hope I haven't confused you too much. I used to write serial protocols for Microsoft for running multi-tasking modems in the early 80's and sometimes I can give too much information in my attempts to help.

Edited by dhbaird
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I got the adaptor to work once. After I removed it from the PC and plugged it back in it quit finding the GPS it even after reboot with dongle in. Same issue with my laptop. It sees there is an adaptor there as far as ,y device manager is concerned, but my GPS software won't detect the GPS itself.

Edited by bonelessi
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I got the adaptor to work once. After I removed it from the PC and plugged it back in it quit finding the GPS it even after reboot with dongle in. Same issue with my laptop. It sees there is an adaptor there as far as ,y device manager is concerned, but my GPS software won't detect the GPS itself.

Try removing the adaptor from the computers as a device using Device manager on your Control Panel. Shut down and Power off everything.

 

Reboot

 

Re-Run the setup software to reinstall the device drivers of the adaptor. Shut down everything and power off.

 

Plug just the adapter in without the dongle connected and let Windows XP find and install the adaptor.

 

If the computer will not find the adaptor after this then you have either

1 a faulty adaptor or

2 you have another device that has grabbed the port. (like a PDA or USB camera link). If that is the case you need to shut down all programs that grab the port and remove them from your start-up options using System info, selective start.

 

If it does find and install the adaptor then shut everything down. (Power off)

 

Power up the dongle and reattach it to the adaptor and reboot.

 

Computer should now find the Comport on the Dongle and asssign it a Comport (Com4 or Com5 most likely)

 

Go to device manager and check to see what comport your new serial port is assigned and configure the map program like EasyGPS to talk with that port.

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OK I think I have some consistency. I need to plug the Belkin in and THEN turn the PC on (like you said). With the other adaptor this (Prolific) will not work. Nothing will work.

 

So I think we may be all set. I just need to turn the PC on with the adaptor in the USB port. Phew :lol:

Odd...Because USB devices are supposed to be "hot swap" meaning you can plug them in or unplug them at any time and "system' should recognize them ...

 

Here is how I find my USB/SERAIL adapter...

 

Easiest solution to find COM port is to go into "Control Panel" >> Select "System " icon >> Select "Hardware" >> Select "Device Manager" >> Scroll down to "PORTS" (COM & LPT) and see what new "port" pops up when you plug in USB/SERIAL adapter cable

 

Mine comes up as "Prolific USB to Serial Comm Port (COM5) "

 

What ever Comm port number USB port is assigned by "system" (COM5 in my case) is Comm port number you need to use when setting up parameters/properties in your software used to communicate with GPS unit through USB/SERIAL adapter cable.

 

Be sure USB drivers for adapter cable are loaded from CD FIRST before trying to plug in USB/Seriall adapter cable.

 

Pretty mush like other user described in previous response..

 

In this cases you probably to clearn out drivers and reinstall them BEFORE you attemp to plug in adapter cable.... Even though BELKIN is brand name, Prolific makes about 90% of usb/serial adapters on market today...

 

Dale

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Odd...Because USB devices are supposed to be "hot swap" meaning you can plug them in or unplug them at any time and "system' should recognize them ...

 

Hi Dale,

 

In an ordinary world you would be correct, that USB can hot swap at ease.

 

The difficulty is the serial side of the adaptor. That still needs to be initialized and set to the correct baud, handshake protocol etc... That best happens at boot up.

 

Can you do it by initializing the port with a search, sometimes. It depends on the unit being initialized. In other words it may not be the adapter that can not be found, it may be the GPS, modem, or other serial device on the other end that is not getting initialized correctly.

 

David

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I sometimes have the same problem with my USB to serial adapter and Windows XP. Yesterday I was getting ticked because I was on the road and couldn't load waypoints into my GPSr. I went into the control panel / system / Device Manager and opened up the port for the USB to serial adapter. Under the Port Settings tab I clicked Advanced, then took both the recieve buffer and transmit buffers down one notch. I also set the com port from 5 down to 2. After that it worked fine.

 

The whole USB to serial thing can be tricky. It requires a bit of finesse, techincal expertise, and sometimes a really big hammer. But usually it works ok.

 

:lol:

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I went into the control panel / system / Device Manager and opened up the port for the USB to serial adapter. Under the Port Settings tab I clicked Advanced, then took both the recieve buffer and transmit buffers down one notch. I also set the com port from 5 down to 2. After that it worked fine.

 

Those are great suggestions... scaling down the transmision speed sometimes works as well.

 

One of the things that also helped when you do that is that by going into the Port settings and changing them, you re-initialized the port when you clicked Okay or Apply. That would have sent the correct parameters to both the USB to Serial Adapter and to the GPS so that they could talk with each other.

 

I once had a serial device, can not remember exactly what at the present that would only take an assignment of Com 1-3, nothing higher. Even though the set-up screen on the device showed Com 4 & 5, selecting them never worked. It was a flaw in the actual logic hardwired on the board.

 

I defeated some of these Com Port Hot swap issues on one older laptop by purchasing a USB Hub. Then I could plug in all of the various USB devices like the wireless mouse, camera, Palm cradle, GPS dongle and Media Card reader at the same time. This gave each device a dedicated USB slot and I had far fewer "device not found" errors.

 

Upon further research I found out that some vendors write their device drivers a bit sloppy in the "surrender port on disconnect" section of them. The result is they initialize fine when you plug them in but they retain control of the USB port when you unplug them. Then you plug something else in and they can not initialize the port.

 

Multi-tasking and multi threading multiple serial communication ports on the same machine is not as easy as it sounds with interupts and buffers and all that. Some of the security patch implementations that Microsoft has implemented in SP2 has made the buffer stuff even a bit more complex. Hackers used to over run the buffers to cause some of the buffers to shut down and that would open up a security "hole" for them to exploit to do malicious things with the computer.

 

Some of those fixes that Microsoft implemented to make your machine safer from that kind of stuff basically screwed up the device drivers on some serial devices.

 

It is critical that you check your vendor for updated drivers from time to time as they will fix some of the flakey behavior of the serial device that was created by the security patches and updates.

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Hi Dale,

 

In an ordinary world you would be correct, that USB can hot swap at ease.

 

The difficulty is the serial side of the adaptor. That still needs to be initialized and set to the correct baud, handshake protocol etc... That best happens at boot up.

 

Can you do it by initializing the port with a search, sometimes. It depends on the unit being initialized. In other words it may not be the adapter that can not be found, it may be the GPS, modem, or other serial device on the other end that is not getting initialized correctly.

 

David

 

 

I think if you will fine that if you set up port paramters in GPS and Software (GSAK-EasyGPS) to same as "default" parameters found in "proparties" for USB/Serial adapter you will not have any connection problems.

 

Did you even know that there is a properties setting for COM port on control panel. Try right clicking 'Port" once you have hot swap - pluged in USB/Serial adapter.

 

By default mine are are:

 

Baud =9600

DataBits = 8

Parity = None

Stop Bits = 1

Flow Control = None

 

The driver "defaults" set in port parameters (Properties) in "hardware" can be adjusted and saved so every time you plug in adapter it will default to desired setting... You have to have software and GPS unit set to match.

 

I still believe most of the "problems" is not having "port defaults" at (initalization-plugin time), software, GPS all set to same paramters.... And boot up has nothing or very little to do with it.

 

Though RS-232 Serial Ports are on way out, it would probably be a little beneficial for one to look up how they function and what parameters do..

 

http://www.arcelect.com/rs232.htm

 

Dale

Edited by Dale_Lynn
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