What is the return to zero function and how is it used?

The RETURN TO ZERO (RTZ) feature is used to help ensure all load cells or sensors are operational and there is minimal binding. When the instrument is calibrated, a millivolt reading from the load cell system is stored in memory for the zero calibration point. If you have any IT summing card with the unit it will also record the individual load cell millivolt readings. When the RETURN TO ZERO diagnostic feature is activated the current millivolt reading is compared to the stored millivolt readings. If the millivolt readings vary by more than the zero tolerance plus motion tolerance an error is generated.

NOTE:  if there is weight on the scale, the RETURN TO ZERO test should fail unless the weight is less than the tolerances listed above.  This is a test to see if the scale returns to its zero starting point when empty.

The HI 1746WS module requires the WS 100 software for all Integrated Technician tests. 
The HI3010 does not support the Integrated Technician summing card.  It uses Smart Diagnostics and the load sensor cables must reach the controller along with the SD option.