A TDS meter is really just an electrical conductivity (EC) meter that has a built-in conversion factor that displays the output in parts per million (ppm) of total dissolved solids (TDS). EC is displayed in µS/cm (but not always) The trouble is that the relationship between the conductivity of a solution and its content varies not only by the concentration of the dissolved ions, but is also based upon the charge and mobility of the dissolved ionic species.
As a very simplified explanation of that, imagine a small ion and a large ion having the same electrical charge. The small ion will find it easier to move in the solution, so "conducts" that charge faster, so gives a higher EC for the same concentration (TDS) in the solution. Likewise, if two ions have the same size, but one has a higher charge than the other, it too will show a higher EC.
I really only use EC as my measurement reading as the others are just calculations based off EC. Not sure about Hanna, but your EC should be a number like 1.0 or 1.5 etc.