MACHCTRL
LAB CASE · P-001

Lab Case P-001: Continuous Dosing Machine

Connect requirements, addresses, Run logic, numeric data and refill control in one training project.

Source distinction: this is a MACHCTRL training lab case, not a commissioned client case. A $1,500 Upwork posting was previously referenced as inspiration, but the original posting body and client requirements were not recovered.

Control goals

  • Hopper weight: 0.0–500.0 kg
  • Load-cell transmitter: 4–20mA
  • Target feed rate: 0.0–1000.0 kg/h
  • VFD speed reference: 0–10V
  • Start refill at 60.0 kg and stop at 400.0 kg
  • Planned behavior: hold the last valid speed command during refill

Current key addresses

DeviceMeaning
X3Local Start
X4Local Stop NC
X5Auto/Manual
X10/X11Safety relay healthy
X13/X14VFD Ready / Fault
Y0VFD Run Command
Y1VFD Fault Reset
Y4Refill Valve
M30Refill Request Latch
D300Load-cell Raw
D310/D311Scaled Weight

Run / Auto logic

M10 = X4 AND X10 AND X11 AND X12 AND X13 AND /X14
SET M0 = M10 AND X5 AND (X3 OR M20)
RST M0 = /M10 OR /X5 OR M21
Y0 = M10 AND ((X5 AND M0) OR (/X5 AND X6))

Speed command selection

Y0 AND X5  -> MOV D100 D120
Y0 AND /X5 -> MOV D110 D120
/Y0        -> MOV K0 D120

Refill hysteresis

D310 <= K600  -> SET M30
D310 >= K4000 -> RST M30
M30           -> Y4

Between 60.0 kg and 400.0 kg, M30 retains its previous state. That creates hysteresis and prevents the valve from rapidly toggling around a single threshold.

The Q5B training prompt temporarily used Y1 for the refill valve. The approved project map uses Y1 for VFD Fault Reset and Y4 for the Refill Valve.

Next design steps

  • Refill permissive and Manual/Alarm interlocks
  • Hold last valid speed during refill
  • Calculate actual kg/h from weight change
  • Automatic correction from target error
  • Scale 0–1000 command to AO raw
  • Load-cell and VFD diagnostics
  • HMI recipes and commissioning test cases