The biggest mistake people make with I2C is dealing with the address. If both A0 and A1 are grounded, the address of the device is 40h as a 7 bit quantity. The value is shifted left one spot to make the address actually sent over the wire as 80h or 81h where the low order bit is the R/W' value. In effect, you write the commands to 80h and read the status from 81h. Those are the only addresses and there is only one register in each direction. See page 29 here:
http://www.ti.com/lit/ds/symlink/ads1219.pdfSome libraries will handle the shift internally and mask in the R/W' bit so you tell them to use address 40h and the code knows what to do with the R/W' bit. Other libraries want you to shift the address (to 80h) and still allow them to mask in the R/W' bit. Getting this part right is the main difficulty with I2C.
For a first approximation, I would write code to read the status register and look for some kind of ID code in bits 0..6. I'm hoping they didn't leave the field 0x00 or 0xff. If I could get a consistent ID, I would know I'm on the right track. Just print the value to the terminal.