I'm using aa NI-8451 USB to I2C convertor and trying to read a device with Labview 8451 read vi. The signals coming out are partially correct.

[lec]

Labview version 8.0. I've had this program working in the past but after shutting down my system it now no longer works. I can find the unit on MAX and it says its working properly.  Using a signal analyser I can see SCL looks good and SDA gives the correct first address but the part doesn't send an Acknowledge. I know the part is working because I run another program thru the parallel port use 3rd party software to verify. I have used 10k ohm pullups and they have worked in the past. I have lots of vi's working in the past before shutting down my computer. Could something have reset? I'm using the same name for the port as last time (USB0). Any ideas.

Thank you.

larry

[Robert M]

Hi Larry,

If it was working before, then you need to isolate what changed.  If you are unable to identify anything, then you may want to try setting it up on another computer.  Sometimes going through the process again will correct whatever changed.  I'm not sure what specifically could cause your described malfunction.  You can try using the recommended 2.2k or 4.7k resistor instead of the 10k.  Your seeing the correct data on SCL and SDA points to the problem being with the part.

Hope this helps,