Checking an isolation amplififer
There should be no connection between the input, the output or the supply except as you have connected externally. Here is the internal block diagram from this datasheet: 



There are three sets of pins: 

a)   9 and 10

b)   5, 6 and 7 

c)   1, 2 and 3 

There should be no continuity between sets of pins, but there will typically be some measurable impedance between pins within a set. Isolation is provided the dual-secondary supply transformer at the top, and by the internal isolation amplifier in the center (the triangle symbol with a gap).