How can I clear the ERREXC error from my HI 2151/30WC?

The HI 2151/30WC, HI1756WS, and HI1746WS have excitation monitor functions that continuously monitors the load cell excitation current. This continually checks for open or shorted load cells and damaged excitation wire(s), including the wires between the instrument and the junction box. At the time of calibration, your controller will use the Current Draw for the load cell system and the Sense Voltage to calculate the Load Cell Resistance. It will store this calculation and then continuously monitor the current draw and sense voltage for the system and compare this new value to the stored value. If the current value deviates more than a +/-11% from the stored value, you will get an Excitation Error condition.

In a system with C2® load sensors, Integrated Technician (IT) computes the correct current and displays alarms if the initial measured current is out of tolerance. In a system without C2® load sensors, the initial current value stored during calibration becomes the standard, whether the initial current is right or wrong.

CAUTION: Do not just re-calibrate to clear an ERREXC. You should verify the load cells are correctly installed and operational. If you calibrate a system with one or more bad load cells, that operating level will be considered within tolerance by the system.

For more information on the excitation monitor setup and system troubleshooting, see the troubleshooting chapter in your controller's manual.

Typical causes of an ERREXC error on a new installation are as follows:

1. Load cell input is actually damaged. Verify individual load cell resistance readings.

2. System is not calibrated or calibration incomplete.

3. System calibrated by a simulator and then load cells were installed. The current measurement stored during calibration is that of the simulator and not the present load cells installed.

4. Load cell sensor wires, on the back of the instrument or in the summing junction box are disconnected or miss-wired. All wires need to be properly terminated.

5. New load cell assembly was installed that has a different capacity or bridge value.

6. If using C2® calibration, was the load cell count correct?

7. Compare readings with the BaseR and the ReadR. A low reading indicates a shorted or miss-wired load cell. A high reading indicates an open or missing load cell. If the current value deviates more than a +/-10% from the stored value, you will get an Excitation Error condition.

*BaseR = the resistance reading taken at power up for C2® load cells, or the reading taken at zero of hard or soft calibration for non C2® load cells.

*ReadR = reads the current resistance and displays that value (this value should match or be close to the BaseR value).

*TestR = tests the base reading against the current reading, and displays R=GOOD or R=ERR.

8. If the BaseR and ReadR are correct, check for bad barriers or miss-wired load cells.

If the ERREXC error is displayed on a formerly operating system:

9. Isolate and measure the individual load cell excitation OHMS and compare to the load cell certificates.

10. If the system is equipped with intrinsic barriers verify the barrier is operational.

11.  Swapping the controller using the SMM can sometimes provide different current draw information. Redo the C2 calibration and the error will stop.  If you do not have C2 load cells, just do the zero under HDcal will correct the problem, however you may need to complete the calibration with a span setting as well.