You can connect floating and grounded input signals to the FieldDAQ device. Make sure that devices you connect to the FieldDAQ device are compatible, as listed in the FD-116xx Specifications.
The FD-116xx provides an IEPE excitation current for each channel to measure the IEPE sensors. Typical IEPE sensors have a case that is electrically isolated from the IEPE electronics. As a result, connecting the sensor to the FD-116xx results in a floating connection even though the case of the sensor is grounded.