Should be ~512 without current through the sensor, assuming you use an Uno.
Connection is simple. Vdd to 5volt, Gnd to ground, Vout to an analogue pin.
Code is the same as an ACS712. Many examples on the net.
What are you trying to measure. AC, DC.
This is a 150/200Amp sensor, so resolution is not that high (~0.5Amp per A/D value).
Leo..