1. Presented by Emil Melamed
UNITRONICS
Loadcell
Presented by Emil Melamed

2. Weighting System Tank (Tara) Net Weight Platform (Dead load) Loadcells
Presented by – Emil Melamed

3. Loadcell Pressure Loadcell Loadcell is based on resistor bridge.
When pressure or tension applied, the bridge goes unbalanced
the potential between +SG and -SG is different from 0
Pressure
Loadcell
Presented by – Emil Melamed

4. Loadcell The potential is proportional to the applied force
and excitation voltage
The polarity of the potential depends on the direction
of the applied force the potential is given in mV/V
Excitation can be DC or Alternating polarity square wave (AC)
AC excitation gives better accuracy
DC excitation can be applied for troubleshooting purposes
Presented by – Emil Melamed

5. LC Signal Processing
LC1/3 is intelligent, microprocessor based expansion module.
It uses an internal 24 bit A/D converter
The output of the A/D converter is called “raw” value
One can select two result formats – 16 bit signed and
24 bit signed
Support two input ranges (gains) - +/-20 mV and +/-80 mV
Gains are software selectable
One can apply offset to the input signal
Presented by – Emil Melamed

6. LC1/LC3 Module Communication
Communication between the PLC and the LC1/3 is done via
commands, given from the PLC
Data such as calibration points, zero, tare…
is stored in the RAM memory of the LC1/3, which is not battery back up.
To retain data on power lost, a “save” command
must be applied to burn ALL the data in module’s EEPROM
Presented by – Emil Melamed

7. Calibration Calibration – matching raw value with weight value
Presented by – Emil Melamed

8. Calibration LC1/3 support up to 12 calibration points
Calibration for at least 2 points must be performed prior to begin weighting operation.
Setting Input range/Gain/Offset must be performed before calibrating.
Zero does not have to be calibrated
Points doesn’t have to be calibrated in any particular order.
Raw value between two point must be at least 256.
Calibration should be performed in greater accuracy than the application needs.
The highest calibration point should be % of max scale threshold.
Calibration cannot be performed if the Representation mode is mV/V.
Presented by – Emil Melamed

9. Acquire Zero Tank (Tara) Net Weight Platform (Dead load) Loadcells
Presented by – Emil Melamed

10. Acquire Zero
Deadload is the load of the platform, where the weight to be measured is located.
In most of the applications, we need the scale to show zero after platform (deadload)
Aquire zero must be performed after calibration.
Aquire zero affects both net and gross weight, which are set to 0.
Aquire zero sets 0 at the moment of performance and is not related to “Zero tracking”.
Use Save calibration to store Zero point to EEPROM
Zero cannot be acquired while running in mV/V mode
If Motion band is activated, Zero cannot be acquired until the scale is stable.
Presented by – Emil Melamed

11. Auto Zero Tracking
Auto zero tracking, when activated, follow Zero point
in a dynamic way.
Presented by – Emil Melamed

12. Acquire Tare Gross = Tare + Net Tank (Tare) Net Weight
Platform (Dead load)
Loadcells
Presented by – Emil Melamed

13. Acquire Tare
Tare value is the weight of the container, where the actual good to be weighted is placed.
The purpose of Acquire Tare is the same as Acquire Zero – to start weighting from value 0.
Presented by – Emil Melamed

14. Gross = Tare + Net weight
Acquire Tare
Acquire Tare sets Net weight to 0
Acquire Tare doesn’t affect Gross weight.
Gross = Tare + Net weight
Use Save calibration to store Tare value to EEPROM
Tare cannot be acquired when running mV/V mode.
If Motion band is activated, Tare cannot be acquired until the scale is stable.
Tare can be read, edited and deleted.
Presented by – Emil Melamed

15. Representation Mode
Once you connect the loadcell and calibrate at least 2 points, you can begin to run application.
You can select one or two values to read continuously from:
Gross weight
Net weight
Net Min. Weight
Net Max. Weight
Scaled to mV/V
Raw value
Default values are Gross and Net weight.
zero must be performed after calibration.
Changing to mV/V influence both readings
Presented by – Emil Melamed

16. Representation Mode
The number of values to be read is set in module’s Hardware configuration.
Presented by – Emil Melamed

17. Representation Mode
Representation mode can be changed during operation independent for each value.
When mV/V representation mode selected, it applies for both values.
In mV/V mode, most calibration procedures are not possible.
Presented by – Emil Melamed

18. Effective Resolution LC1/3 has 24 bit internal A/D converter.
Min. conversion time per loadcell is 12.5 ms.
The effective loadcell resolution depends on several parameters including gain setting, input span used, the amount of uncompensated differential offset
and the applied input noise.
Presented by – Emil Melamed

19. Effective Resolution
Presented by – Emil Melamed

20. Effective Resolution
The number of loadcell inputs used per expansion module affects the sampling rate of each of them, resulting in lower filter depth and effective resolution.
One way to increase the effective resolution is to disable all other loadcells. This is recommended during calibration procedures.
Presented by – Emil Melamed

21. Effective Resolution
Presented by – Emil Melamed

22. Motion Band
When the weight on scale changes, the scale needs time to stabilize.
Motion band determines the change in weight+ the module uses to decide if the scale is in motion.
LSB of Hardware Status messages turns ON when the scale is in motion and OFF when the scale is steady.
Motion band method must be activated to start this function.
If the scale is not calibrated, In motion bit is always active.
If In motion bit is active, Acquire Zero/Tara cannot be performed.
Filter active band must be equal or great than in motion tolerance.
Presented by – Emil Melamed

23. Motion Band
Presented by – Emil Melamed

24. Filter and Rounding
Filter and rounding method changes the default filter parameters and rounding of weight.
The reading value can be rounded by 2, 5, 10, 20, 50 and 100.
Rounding smoothes the weight reading.
Rounding cannot be performed for mV/V and Raw values.
Presented by – Emil Melamed

25. Filter and Rounding
Presented by – Emil Melamed

26. Filter and Rounding
Settling time is the time, used by the filter to settle to the final reading.
Minimum settling time rises with the number of active loadcells.
Active band is the band, where filtering takes care.
Presented by – Emil Melamed

27. UNITRONICS
Thank you!