USB serial follies

I have a commercial usb-serial dongle that uses the Prolific chip.

If I plug it into one USB connector on my PC, it comes up as COM4 and works.

If I plug it into a different USB connector, XP tells me the driver is bad and has to be reinstalled.

If I plug it into my USB hub, it shows up (in device manager) as COM D and says that something's wrong.

Makes no sense to me. Any ideas?

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John Larkin         Highland Technology, Inc 

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Reply to
John Larkin
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That's just the way windows doesn't work.

Reply to
tm

The XP usb stack was implemented wrong. WIN7 usb stack was implemented correctly. Get a converter from USconverters.com they will work on either system.

I've had converter (GM something) that did not work with a hub. The converter from usconverter works thru the hub. The prolific drivers are not perfect, there was a version that did not work properly. Delete the inf file , reboot and start over.

Cheers

Reply to
Martin Riddle

Maybe I should get their MiniPro, which uses the FTDI chip. We use the FTDI in a couple of our products and it seems to work.

Thanks

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

The one I use is the Pro XS8801, I think they all have the FTDI chip. After switching to these I never had anymore problems.

Cheers

Reply to
Martin Riddle

genuine or counterfeit PL2303? whose driver are you using prolific's or the vendors?

XP loads a suitable driver if you plug it in the "one port" "other port" and "hub" gets the default driver which is the wrong one.

formatting link

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Reply to
Jasen Betts

Don't know! It's a Trendnet TU-S9, from Amazon.

I didn't install any drivers. XP just worked, and still works, as long as I plug the converter into the same USB slot. I don't like to install drivers if I can avoid it.

Now that's weird.

I guess I'll order a few FTDI-based converters.

Thanks

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

a

I have had much better luck with the FTDI chips/drivers than any others. The correct response from the OS should be that the dongle just changes COM ports when moved around to other ports. I have a StarTech 4 port adapter that has the cool option of keeping the same set of COM ports no matter where the device is in the USB chain. That way my instruments don't get bounced around if Windows decides to re-enumerate the USB devices, like after an update.

Jim

Reply to
WangoTango

a

Agreed, the converters with FTDI chips seem to work best in our products too.

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Regards, 

Adrian Jansen           adrianjansen at internode dot on dot net 
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Reply to
Adrian Jansen

Power level settings for your USB ports or, the driver has a problem with the high device number being assigned.

Some software will not look above a certain number for a COM port..

Jamie

Reply to
Jamie

Some Windows USB drivers seem to (want to) remember the device's identity and location, based on the topology of the USB tree structure... "the device plugged into port 3 of bus 5 is COM5". A lot of the Prolific-based adapters (and their clones) are not uniquely identified on the bus... they don't have unique serial numbers... and thus the drivers can't remember their COM binding by anything other than port location. If you switch ports, it's seen as a "different device" because it's at a different location... it's no longer COM5 (e.g.).

And, some of these drivers can handle / remember only a single instance of the device. If you switch ports, the "old device" has to be forgotten / de-registered and a new one registered, and (in these drivers) this is done by declaring the driver install "stale" and requiring that the driver be uninstalled and reinstalled.

Not a good programming practice.

From your "COM D" comments, I'd guess that this particular driver is so poorly coded that it can only "remember" or "manage" a device which is connected directly to one of the ports on a root hub. That's a really *poor* programming practice!

The FTDI devices seem to have at least two advantages here:

- The drivers are generally written a lot better.

- The driver doesn't have to try to "remember" a device's identity by its USB tree location. Each FTDI serial adapter has a unique serial number, which is available via the bus, and the driver can bind a specific COM port to a specific device serial number and will re-create the correct binding when you plug in the device, no matter which port you connect it to (and no matter in which order the system's USB hubs happen to enumerate at boot time or when they are powered up).

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Dave Platt                                    AE6EO 
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior 
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Reply to
Dave Platt

y

and if you use the ftdi driver directly you can open a device based on serial number so it doesn't matter what is was assigned

-Lasse

Reply to
langwadt

Not really. The FTDI drivers also crap out real quick. I have a lot of problems with them. The best USB serial converters I came across are based on the CP2102 chips from Silabs.

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Reply to
Nico Coesel

Especially if the default driver is the only one you have installed.

People used to bitch that RS232 wasn't a rigorous standard, but it was never as much trouble as when mated with USB and plug-n-play standards, or Microsoft's implementation of same.

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Reply to
Tom Del Rosso

The real and clone MAX232 chips usually don't meet the basic electrical specs, either. Especially max input voltage withstand.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

RS232 has settled a lot. Thirty years ago, I had plenty of fun wrestling with RS232 until it worked. These days things are simpler. Nearly everyone ignores the hardware handshake, which simplifies things quite a bit. The PC industry settled DCE vs. DTE issues. Software often figures out the right baud rate, which simplifies things a bit more.

USB is not designed to be universal. It's designed to generate revenue.

Jeroen Belleman

Reply to
Jeroen Belleman

Police are looking for a Serial port killer in Houston TX. He's committed 3 killings since the weekend, and is still at large. Please contact the Houston police department or the FBI if you see the guy. He will be armed and is extremely dangerous.

Attorney Goldberg

Reply to
Attorney.Goldberg

The serial port killer is often sitting on a chair higher or lower than the chair used by the victim.

Check for ground potential differences.

Reply to
upsidedown

OH. Not related to EMI killing my parallel port..

Reply to
Robert Baer

Last seen driving an Aston Martin DB9?

Reply to
Spehro Pefhany

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