MCP444x/446x Potentiometer ladder and LV 2011 / USB-8451

[galatisa]

Hi,

I'm trying to write data to the MCP444x/446x ladder which has an I²C bus. For that I'm using the USB-8451 controller with pull ups.

I used the example VI coming with LV called "General I2C Write". The part of the VI that adresses my i²C slave device which is on Adresse 5C works fine with no errors but when it goes into writing the data

 bytes i want to write to the slave i always get the -301742 error.

If you open the attachement at chapter 7 the writing and bit/byte definitions are shown. 

I have to ad that my device does not send back an Acknowlegment bit but i do not think that is the issue here. 

If i watch the SDA and SCL lines on my scope i can very well see that the adress command is being issued on the bus.

[Topper_Harley]

Hi Galatisa,

my grasp of your setup is the following:

You are using a USB-8451 I2C device with LabVIEW. The USB-8451 is the Master device. When trying to communicate with a slave on address 5C you get error -301742.

Is this correct?

Maybe these documents are of some use for you:

Using I2C with LabVIEW and the USB-8451

https://www.ni.com/en/support/documentation/supplemental/21/using-i2c-with-labview-and-the-usb-8451....

Please answer these questions:

Have you been able to establish communication with any other slave device on the I2C bus?

What version of LabVIEW are you using?

What bus transfer rate did you configure?

What version of NI-845x driver software are you using?

Regards, Topp

[galatisa]

Have you been able to establish communication with any other slave device on the I2C bus?

No because there is no other device!

What version of LabVIEW are you using?

2011

What bus transfer rate did you configure?

32kHz

What version of NI-845x driver software are you using?

Upo to date! Xchecked that with NI!

Since I wrote the original post NI clarified that this can not work as long as my slave device does not return an ACK bit because the USB8451 runs an philips controller and does not allow the ACK bit to be ignored. 

So my problem has to do with this and can not be solved!

[Topper_Harley]

I am sorry that your setup is not going to work as you expected.  Please leave a message in case you need any additional informaton on this.