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USB-Serial Adapters Causing Blue Screens

Question asked by Scott-S on Mar 18, 2010
Latest reply on Jul 3, 2010 by VeeCritter

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Hello fellow Vee-ers;

I have a Vee program that sends and receives bytes over a serial port at 115K. I have it working great with my desktop that has a real com port. But every usb to com port adapter I have tried (I need this to run on a laptop) gives me a BSOD (blue screen of death) at some random interval. I have tried 3 different brands of Uarts/adapters and I made sure I was using the latest drivers, but I still cant get it reliable. It also does this on my desktop if I use the usb adapter (but not when using a real com port).

The other issue is of course the speed. When the program is running is it very slow using the usb-serial adapter. Since USB is much faster than serial, I wouldnt expect a bottleneck, but it sure does.

Here is my question: Does anyone here know what brand USB-Serial adapter is the most reliable? Has the best drivers etc?

I am using WIndows XP Pro and Vee 9.0

I have tried a Silicon Labs (CP2103) and a Keyspan adapter. I also tried a third one but don't have it around and don't remember what brand it was.

Any help would be appreciated.

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UndeadBob Apr 6, 2010 5:37 AM

115k. wow, never used anything that high. I'm no expert, but you don't seem to be getting any other responses.

Any USB-serial driver is an emulation process, so there will be speed loss regardless. Is it possible to tone down the baud rate on the device?

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gatekeepr69 Apr 12, 2010 11:35 PM

Have you tried FTDI's adapters? they work very reliably and offer both a "Virtual Com Port" and "DLL" method of access. The DLL method may work better due to your high speed.

your retail adapters may be FTDI based. FTDI drivers also allow you to adjust the latency of the device itself under the com port propteries in device manager the default is 16ms which may be causing problems.

How long is the serial cable you are using?

How are you interfacing to the COM port through VEE? We use a commercial activex control communicating through the virtual com port which works quite well.

When you get a blue screen, what module is it occuring in, you should see some kind of DLL listed, also look in the event viewer to any clues as to where the fault is occuring.

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Scott-S Apr 13, 2010 6:36 AM

Thanks for the replies.

I am stuck using the 115K because the test fixture I am interfacing with is an old legacy one and I have no way of changing the firmware in it.

I am currently just using the built in Vee Direct IO functions to send and receive bytes on the the com port.

The next time I get the BSOD, Ill take a better note of what module is failing.

I am only using a 1 meter cable on the serial side, so I hope that is not an issue.

I will take a look at the FTDI.

I think the best way would be to move to the DLL method. The "virtual" com port stuff is a bit to reliant on how well they did the drivers.

Again, thanks for the input. I'll pst again when if I make any progress.

Scott

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VeeCritter Jul 3, 2010 10:59 AM

Try using the .NEt SerialPort object under System. That solved a strange hanging problem i had using the VEE serialport over USAB.

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4 Replies

UndeadBob Apr 6, 2010 5:37 AM
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115k. wow, never used anything that high. I'm no expert, but you don't seem to be getting any other responses.

Any USB-serial driver is an emulation process, so there will be speed loss regardless. Is it possible to tone down the baud rate on the device?
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gatekeepr69 Apr 12, 2010 11:35 PM
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Correct Answer
Have you tried FTDI's adapters? they work very reliably and offer both a "Virtual Com Port" and "DLL" method of access. The DLL method may work better due to your high speed.

your retail adapters may be FTDI based. FTDI drivers also allow you to adjust the latency of the device itself under the com port propteries in device manager the default is 16ms which may be causing problems.

How long is the serial cable you are using?

How are you interfacing to the COM port through VEE? We use a commercial activex control communicating through the virtual com port which works quite well.

When you get a blue screen, what module is it occuring in, you should see some kind of DLL listed, also look in the event viewer to any clues as to where the fault is occuring.
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Scott-S Apr 13, 2010 6:36 AM
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Thanks for the replies.

I am stuck using the 115K because the test fixture I am interfacing with is an old legacy one and I have no way of changing the firmware in it.

I am currently just using the built in Vee Direct IO functions to send and receive bytes on the the com port.

The next time I get the BSOD, Ill take a better note of what module is failing.

I am only using a 1 meter cable on the serial side, so I hope that is not an issue.

I will take a look at the FTDI.

I think the best way would be to move to the DLL method. The "virtual" com port stuff is a bit to reliant on how well they did the drivers.

Again, thanks for the input. I'll pst again when if I make any progress.

Scott
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VeeCritter Jul 3, 2010 10:59 AM
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Try using the .NEt SerialPort object under System. That solved a strange hanging problem i had using the VEE serialport over USAB.
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USB-Serial Adapters Causing Blue Screens

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