To follow are some common questions related to the linux D2XX driver which may 

solve some issues before conacting our support.



Q. 	FT_ListDevices by number returns 0 even thought the device is listed in 

	USBVIEW, why?

A. 	It is possible you have not added your own device VID and PID to the driver. 

	Use the FT_SetVIDPID function prior to calling any of the D2XX APIs.



Q. 	Why does FT_Open/FT_OpenEx return FT_DEVICE_NOT_OPENED?

A.  The VCP driver has ownership of the device and the D2XX driver cannot claim

	the interface. Either change the VID and PID of the device so that it will not 

	be loaded by the ftdi_sio driver or unload the ftdi_sio driver using the 

	rmmod ftdi_sio command (you must also remove the usbserial in the same manner).

	Please note this issue is suppressed in version 0.4.4 and later. Although you may 

	find some issues related to this. If you are having trouble using FT_open/Ex please

	contact support with your kernel version details.



Q.	Why does the linux version of the D2XX driver behave in a different way to the windows 

	driver? 

A. 	Please contact support (support2@ftdichip.com) with your query as you may have found a bug.

	We want the drivers to match as closely as possible and your comments may help us achieve this.



Q. 	Can I obtain the source of the D2XX driver?

A. 	Is is company policy not to release any source code as some of the linux driver is derived from the 

	Windows based drivers which we currently do not want to release. If you must have the source code to 

	your project you may try libftdi which is an open source project.

		

Q.	I have trouble compiling the sample applications.

A.	The solution may vary but could be one of the following:

	1. Library not isntalled in the correct area - please check documentation.

	2. Incorrect header files included in current directory. WinTypes.h and ftd2xx.h are the two main header

	   files required.

	3. The pthreads library is required for the library itself. Please ensure this is installed properly on 

	   your system.

	   

	Compilation errors are mostly simple problems that can be fixed in a very short period. 

	Type the error message output by the compiler into a suitable search engine (www.google.com)

	which may provide you with some clues on how to fix your compile problem. If you are still stuck 

	then you can contact our support for some hints on how to solve your problem.

	

Q. 	Can I mix and match D2XX with the ftdi_sio driver?

	Some customers have had success with this feature however we have noted some issues between 2.4 and 2.6 kernel 

	trees regarding device indexing (for example FT_Open(0, &ftHandle) does not correspond to the /dev/ttyUSB0 

	device). If you want to try this method please take care as due to the inconsistency between kernels we cannot 

	support this feature.

	

Q.	I have an issue with a 2.6 kernel.

	We have noted some issues with certain kernels of the 2.6 branch. Currently these stand at 2.6.4, 2.6.7, 2.6.8 

	and	2.6.11. We try to test with as many kernels as practibly possible prior to release but if you see an issue 

	that is	not one of the above kernels then contact support and we will test that kernel on site.

	











