FTDI virtual com port driver (VCP) and Labview 2009 - random connection loss

[mattvx]

Hi,

I am using an FTDI chip to go from USB to serial communication (FTDI Driver: 2.06.00). It seems to work at first but then after some time the connection gets lost ("connection for the given session has been lost" or "I/O error"). This happens in MAX as well as the built executable of the program I am running. Latest VISA drivers are installed - 4.6.  I have tried flushing the buffer before and after communication with both visa clear and visa buffer flush vis. The lost connection seems to happen randomly. 

I have seen other threads about this issue but they never reach a resolution. One thing i notice is that there are two FTDI devices in this system and only one fails, however when I unplug the working device the one that fails is able to connect again.  

To sum up here are the system specs:

Windows XP SP3

FTDI 2.06.00 and older 2.04.02 drivers both fail.

2 FTDI devices on the system - they do get assigned different COM ports

Labview 2009 run-time

VISA 4.6 run-time

Thanks for any help. 

[mattvx]

Update: It seems that as long as both usb to serial devices are plugged into the same bus it works. For instance, communication is stable if they are both plugged into a 3rd party usb hub which is then plugged into one usb port on the computer. Or if they are both plugged into separate but adjacent usb ports on the computer it also works. USB Ports on opposite sides of the computer do not work ie front and back on a desktop or opposites sides on a laptop. 

[mattster]

Hi,

I have the same problem – are you using VISA (virtual COM ports) or the provided ftd2xx.dll with D2XX_Functions ?  (I have experienced lost connections with both)

I have tried just about everything without any improvement – even resorted to a virgin computer (XP SP3) with LabView executable (LV 9.0f2 runtime), no VISA and FTDI 2.06.00 drivers.  I have also spent hours tweaking the configuration parameters – problem still there.  I have noticed that some USB ports on different busses seem to help (as you noticed) – but the problem eventually returns - it just takes a bit longer.

If you have any news or a solution I would greatly appreciate an update.

[mattvx]

We've been using a 4port USB hub with all the FTDI devices plugged into it. The problem hasn't reoccurred yet. I am using VISA to communicate with the virtual COM ports. 

[mattster]

Just now I am using a Belkin Hi-Speed USB 2.0 7 port hub (F5U237) and the FTDI device seems to work - this hub is also externally powered. Same computer I only get about 5-10 minutes if I connect directly.

Could you please let me know the make and model of your hub and if it is externally powered?

[mattvx]

We use Targus ACH63US Super Mini USB 2.0 4-Port Hub. It doesn't require external power but if you have a high power device you will have to plug the Targus hub into two usb ports on your pc (one provides power and the other does power and data transfer). They provide the usb Y cable to do this.

[Lunarfur]

Hello,

although the thread is older, the solution may lie in the serial number within the FTDI Chip. As they are usually identical windows only detects them as one device. You can allow several FTDI Chips connected if you programm a different serial number on an EEPROM with the tool provided by FTDI

http://www.ftdichip.com/Support/Utilities.htm#FT_Prog

Regards