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UNITRONICS

UNITRONICS. Loadcell Presented by Emil Melamed. Weighting System. Tank (Tara). Net Weight. Platform (Dead load). Loadcells. Presented by – Emil Melamed. Loadcell. Loadcell is based on resistor bridge. When pressure or tension applied, the bridge goes unbalanced

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UNITRONICS

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  1. UNITRONICS Loadcell Presented byEmil Melamed

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

  3. 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 pointsmust 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 80-100% 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 aftercalibration. • 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. 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 aftercalibration. • 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 methodmust 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!

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