Why does a digital 0,1,1,0 convert to a -1, 0, 0, -1?

[flycast]

Using Digital to Analog waveform function why does the following:

0

1

1

0

convert to:

-1

0

0

-1

Code:

Result:

I was expecting:

0

1

1

0

[Darin.K · Accepted solution]

The data format defaults to offset binary, you want unsigned binary. 

[flycast]

That was indeed it. Now, what is signed binary and why would it be used? I've honestly never heard of that before.

Actually a better question. If a waveform has been saved in signed binary in a TDMS file is there a way to detect that when loading and reading the TDMS file?

[JÞB]

The waveform datatype will be in the waveform attributes. 

You may have to play detective on the exact attribute name but, "NI_Datatype" might be close.  The TDMS import addon for Excel should help you find out.