Design A Weight Based Automatic Filling System
Budget: $50 – $150 USD
Project Overview
We’re building a scale that will later integrate with a filling valve to create an automatic filling system.
Scale should handle 50 - 750 kg. The scale will use a platform to measure the weight with four load cells under it, and the signals from the load cells will be sent to the controller via a junction box. The controller will send that data to the PLC using either RS-232 or RS-485 port.
The PLC will display the current weight on the UI screen. And PLC can control the filler machine with three signal types: filling valve full open, filling valve 30% open, filling valve shut off, depending on the weight being read on the scale at that moment. Also, the PLC has been able to communicate in both directions with the controller and the screen to set zero/tare, set the target weight, and run weight calibrations.
System Components
Scale platform(1.5 m × 1.5 m) and load cells:
The scale platform uses four stainless steel shear beam load cells, mounted on load cell feet, to measure weight.
Cables & shielding:
Proper cables and shielding must be used to connect all components without affecting the system’s accuracy and to improve performance.
Junction box:
Stainless steel 4 channel junction box with corner trim. It adds the four load cell signals together and sends a calibrated signal to the controller.
Controller:
It will send the weight to the PLC using RS-232 or RS-485 port, and it should allow for at least 3 point weight calibrations.
Communication layer:
RS-232 or RS-485 must be bidirectional for the data interface between the controller and PLC. Input current reading weight from the controller to the PLC or input from the PLC to the controller to reset the zero/tare and calibrations.
PLC control unit:
Receives weight data from the controller.
Executes control logic and valve position commands.
Communicate with the UI interface to display data.
Send a zero/tare signal to the controller.
Set the target weight to fill.
When a calibration is needed, enter calibration mode and set the calibration weight.
Filling valve control (3-stage signal logic):
The material to be used a solid adsorbent such as silica gel with bead diameter from 0.5 mm to 10 mm. The filling valve should take 3 signals.
Signal 1 – Full open: Activated when filling < 90% of target weight.
Signal 2 – 30% open: Activated between 90–99% of target weight.
Signal 3 – Shut off: Triggered at 100% target weight (filling complete).
User Interface:
Target filling weight setting
current filled weight display
weight reset function(zero/tare)
Weight calibration
System Workflow
The user will load an empty drum on the platform and set zero/tare.
The operator sets the target weight on the user interface.
The controller reads live weight from load cells via the junction box.
The PLC receives weight data from the controller (via RS-232 or RS-485).
The PLC compares live weight vs. target weight and outputs control signals to the filling valve:
<90% of the target filling weight → Filling valve full open
90 - 99% of the target filling weight → Filling valve 30% Open
=100% of the target filling weight → Filling valve shut off
Valve closes completely once the target weight is reached, and the system signals 'Filling Complete.'
System can be reset manually for the next cycle.
Expected Deliverables
Full system drawing.
Component list with vendor links (load cells, junction box, controller, Arduino, valve, screen, etc.)
Per item expected cost of material in a list format.
Control logic flowchart and PLC program.
User interface layout and testing procedure.
Assembly strategy.
Fabrication drawing for the balance.
The freelancer should be available for up to five review sessions, each consisting of a one hour meeting to discuss and evaluate their work.
Project Milestone
Milestone 1 (30% of the project cost):
Full system drawing, Component list with vendor links, and Per item expected cost of material in a list format.
Milestone 1 (40% of the project cost):
Control logic flowchart and PLC program, User interface layout and testing procedure.
Milestone 3 (30% of the project cost):
Assembly strategy and Fabrication drawing for the balance.
We’re building a scale that will later integrate with a filling valve to create an automatic filling system.
Scale should handle 50 - 750 kg. The scale will use a platform to measure the weight with four load cells under it, and the signals from the load cells will be sent to the controller via a junction box. The controller will send that data to the PLC using either RS-232 or RS-485 port.
The PLC will display the current weight on the UI screen. And PLC can control the filler machine with three signal types: filling valve full open, filling valve 30% open, filling valve shut off, depending on the weight being read on the scale at that moment. Also, the PLC has been able to communicate in both directions with the controller and the screen to set zero/tare, set the target weight, and run weight calibrations.
System Components
Scale platform(1.5 m × 1.5 m) and load cells:
The scale platform uses four stainless steel shear beam load cells, mounted on load cell feet, to measure weight.
Cables & shielding:
Proper cables and shielding must be used to connect all components without affecting the system’s accuracy and to improve performance.
Junction box:
Stainless steel 4 channel junction box with corner trim. It adds the four load cell signals together and sends a calibrated signal to the controller.
Controller:
It will send the weight to the PLC using RS-232 or RS-485 port, and it should allow for at least 3 point weight calibrations.
Communication layer:
RS-232 or RS-485 must be bidirectional for the data interface between the controller and PLC. Input current reading weight from the controller to the PLC or input from the PLC to the controller to reset the zero/tare and calibrations.
PLC control unit:
Receives weight data from the controller.
Executes control logic and valve position commands.
Communicate with the UI interface to display data.
Send a zero/tare signal to the controller.
Set the target weight to fill.
When a calibration is needed, enter calibration mode and set the calibration weight.
Filling valve control (3-stage signal logic):
The material to be used a solid adsorbent such as silica gel with bead diameter from 0.5 mm to 10 mm. The filling valve should take 3 signals.
Signal 1 – Full open: Activated when filling < 90% of target weight.
Signal 2 – 30% open: Activated between 90–99% of target weight.
Signal 3 – Shut off: Triggered at 100% target weight (filling complete).
User Interface:
Target filling weight setting
current filled weight display
weight reset function(zero/tare)
Weight calibration
System Workflow
The user will load an empty drum on the platform and set zero/tare.
The operator sets the target weight on the user interface.
The controller reads live weight from load cells via the junction box.
The PLC receives weight data from the controller (via RS-232 or RS-485).
The PLC compares live weight vs. target weight and outputs control signals to the filling valve:
<90% of the target filling weight → Filling valve full open
90 - 99% of the target filling weight → Filling valve 30% Open
=100% of the target filling weight → Filling valve shut off
Valve closes completely once the target weight is reached, and the system signals 'Filling Complete.'
System can be reset manually for the next cycle.
Expected Deliverables
Full system drawing.
Component list with vendor links (load cells, junction box, controller, Arduino, valve, screen, etc.)
Per item expected cost of material in a list format.
Control logic flowchart and PLC program.
User interface layout and testing procedure.
Assembly strategy.
Fabrication drawing for the balance.
The freelancer should be available for up to five review sessions, each consisting of a one hour meeting to discuss and evaluate their work.
Project Milestone
Milestone 1 (30% of the project cost):
Full system drawing, Component list with vendor links, and Per item expected cost of material in a list format.
Milestone 1 (40% of the project cost):
Control logic flowchart and PLC program, User interface layout and testing procedure.
Milestone 3 (30% of the project cost):
Assembly strategy and Fabrication drawing for the balance.