I2C Communication using FT2232HL in LabView : Read Error

[Ash.Bad]

Hi,

I am using FT2232HL to communicate with an I2C device.

I am using the MPSSE I2C API calls.

I am able to successfully Write to the device. Both my GPIO Read and Device Read does not work.

I am able to observe the scope timing, and the Read Data is correct. it is just that when I call the function in LabView, it always shows up as FF. Same for GPIO Read as well.

I am using LabView 2013.

Thanks for the helps.

[Machop]

Can you provide more information about the issue you are having, like the configurarion on VISA.

 There ir a forum that explains a simular issue and it can be related with the VIS configuration:

https://forums.ni.com/t5/Instrument-Control-GPIB-Serial/Reading-IMU-via-RS-485-Output-Missing-Packet...

[Ash.Bad]

Thank you for the response.

I was able to investigate a bit further.

Now, I do not see the "FF" read error. But something more strange.

I have a successful Write to slave and a Read from Slave if the register does not contain "0x00__".

Included the screenshots of 2 different scenarios:

1. Register read when the data is not 0x00_ _ .

2. Register read when the data is 0x00_ _.

The third screen shot is the Read_Device driver API VI. everything seems to be working except reading the default data of "0x000098"

Thanks for the help.

[Ash.Bad]

can someone please comment on the above issue reported?

Thanks

[rolfk]

Your Call Library Node needs to pass the data as Pointer to an Array of U8. When you configure it as a C String Pointer, LabVIEW will on return terminate the string on the first 0 byte it encounters in the string. This is because C strings are by definition terminated by a 0 byte. If you want to pass a binary buffer to a DLL that can return NULL bytes in it, you need to pass that buffer as Byte Array!

[Ash.Bad]

Hi Rolf,

Thanks for the response.

Is this a change required in the DLL file itself. 

Because I am not able to connect anything other than String to that node.

It shows a source and sink mismatch error. The input to the Buffer node is String.

Is there anything I can do to alleviate this problem?

Thanks

Ashwin

[rolfk · Accepted solution]

You need to change the data type inside the Call Library Node configuration for the uint8 *buffer parameter. It is now configured as C String Pointer but you need to configure it as Array of Unsigned 8 Bit Integer, passed as Array Data Pointer.

Then you can also throw away the Byte Array to String and String to Byte Array nodes.

[Ash.Bad]

Hi Rolf,

Thank you for your inputs. I was not aware that I could configure the datatype on the call library node.

I works great now. I appreciate your help on this.

Regards

Ashwin

[IlanMazuz]

Hi,

PLS send me your code to ilanmazuz4@gmail.com

thank you.

Ilan Mazuz

[visi_IE]

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@Ash.Bad wrote:

Thank you for the response.

I was able to investigate a bit further.

Now, I do not see the "FF" read error. But something more strange.

---

Hello,

Can you please explain how did you get rid of the "FF" while reading from slave? I am facing a similar issue with FT232H device and the MPSSE I2C library.

Thank you in advance.