A09 Manual Offset

Definition

Corrects fixed errors that do not vary with flow (zero offset). A09 is added to or subtracted from the instantaneous flow. Default: 0.0.

Parameters A09 (Correction Mode) and A02 (Scale Factor) allow adjustment of flowmeter reading deviations.

$$\text{Corrected Instantaneous Flow} = A_{02} \times \text{Measured Instantaneous Flow} - A_{09}$$

Calibration Examples (Click to Expand)

1. Error Caused by Liquid Density

Example – 50% Sulfuric Acid Assume the liquid is sulfuric acid with a specific gravity of 1.4. Actual measured weight: 26 tons. The flow meter displays 20,004 L. Converted weight: 20,004 × 1.4 = 28,005.6 kg (≈ 28 tons) → the reading is higher than the actual value.

Step 1: Adjust the A02 scale factor

$A_{02} = \frac{\text{Actual Weight}}{\text{Flow Meter Displayed Weight}}$ = $\frac{26\ \text{tons}}{28\ \text{tons}} \approx 0.928$

Set A02 = 0.928, then the flow meter–calculated weight ≈ 25.98 tons, close to the true value.

Step 2 – Fine adjustment using A09:

• After adjusting A02, readings may be accurate at high flow, but small deviations can remain at low flow or when the pump starts.

• Adjust A09 to compensate for fixed offset errors. For example：

• If readings consistently exceed the true value by 0.1 ton, set A09 = 0.1, and the system will automatically subtract this from the calculated weight.

• If readings consistently fall short of the true value by 0.1 ton, set A09 = - 0.1, and the system will automatically add this value to the calculated weight.

2. Error Caused by Analog Output

Example The user is using the analog output and finds that the receiving device (e.g., PLC) does not match the value shown on the flow meter.

The meter display shows 0 (no flow in the pipe), but the output current is 4.1 mA instead of the standard 4.0 mA. After conversion at the receiving end, this results in an incorrect flow reading of 0.98 L/min (zero offset).

Step 1: Use Simulation Mode to Check for Scaling Error

If the displayed flow value appears incorrect (for example, a flow reading when no liquid is present), first use Simulation Mode to verify whether a scaling error exists. Refer to the Simulation Mode section for detailed operation.

Enable F02 Simulation Mode, then go to E06 and enable the analog output content (recommended: Flow Rate). Next, enter F01 to set the simulated flow value and observe the reading on the receiving device.

For example, when the simulated value is set to 60 L/min but the receiving end shows 58.41 L/min, this indicates an overall scaling error (reading too low).

After testing with Simulation Mode, it can be confirmed that the issue is not only a zero offset, but also an output scaling error.

Adjust the A02 scale factor

$A_{02} = \frac{\text{Actual Weight}}{\text{Flow Meter Displayed Weight}}$ = $\frac{26\ \text{tons}}{28\ \text{tons}} \approx 0.928$

Set the A02 value to 1.027. After this adjustment, the flowmeter’s converted reading shows a weight of approximately 58.42, approaching the true value of 60.

Step 2: Eliminate the Remaining Fixed Offset (Zero Point Shift)

After adjusting A02, the readings are accurate at high flow rates, but small deviations may still occur at low flow rates or when the pump starts at a fixed flow. To correct this fixed offset error, you can fine-tune the A09 value.

Adjusting A09 to Correct Flow Values

For example, after the user exits simulation mode and the flow returns to zero, if the receiving end still shows a reading of 0.98, set A09 to +0.98. The system will automatically subtract this value from the calculation, effectively zeroing the meter’s reading.

Notes

1. Setting A09 to a negative value turns the subtraction in the formula into addition, adding a fixed value to the instantaneous flow reading.

2. The unit of this parameter follows the system’s configured units; to change units, adjust the B parameters.

Operation Procedure

Button Functions (Click to Expand)

The main unit has four buttons. The bottom line (Line 3) of the LCD displays the current function of each button. Under normal operation, the button functions are as follows:

• Blue Button: Leftmost button: Return, exit, or save settings.

• Gray Direction Buttons:

  • Left Gray: Previous Page, decrease value, or select item

  • Right Gray: Next Page, increase value, or select item

• Orange Button: Rightmost button: Enter settings, edit, or confirm selection

Do not hold buttons for extended periods to avoid damage.

Button functions may change depending on the operation context to improve usability or prevent accidental presses

Calibration Offset Function (Click to Expand)

Used to correct flowmeter reading deviations.

Related Parameters: A02: Scale Factor, A09: Offset Flow

1

A02 Scale Factor Setting

A02 Scale Factor Setting Steps
• From the main screen(green backlight), 
  press Orange Button(Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select A. Measurement, press Orange Button(Enter).
• Use Gray Arrow Buttons to select A02 Scale Factor, press Orange Button(Enter).
• Use Gray Arrow Buttons to choose the digit to adjust(highlighted in dark gray).
• Press Orange Button(Edit) to enter adjustment mode.
• Adjust digits: Left Gray Button to increase, Right Gray Button to decrease.
• Press Orange Button(Set) to confirm each digit; repeat for other digits as needed.
• After all digits are set, press Blue Button(Save).
Confirm by pressing Orange Button(Save) (or Blue Button(NOT) to cancel).
• Press Blue Button(ESC) to return to the main screen(green backlight).

2

A09 Manual Offset Setting

A09 Manual Offset Setting Steps
• From the main screen(green backlight), 
  press Orange Button(Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select A. Measurement, press Orange Button(Enter).
• Use Gray Arrow Buttons to select A09 Manual Offset, press Orange Button(Enter).
• Use Gray Arrow Buttons to choose the digit to adjust(highlighted in dark gray).
• Press Orange Button(Edit) to enter adjustment mode.
• Adjust digits: Left Gray Button to increase, Right Gray Button to decrease.
• Press Orange Button(Set) to confirm each digit; repeat for other digits as needed.
• After all digits are set, press Blue Button(Save).
Confirm by pressing Orange Button(Save) (or Blue Button(NOT) to cancel).
• Press Blue Button(ESC) to return to the main screen(green backlight).

3

Calibrate Verification

Verify whether the calibration result meets expectations by checking if the calibrated flow value matches the target value. If not, readjust K03 (Scale Factor) or K04 (Flow Offset) and repeat steps 2–4.

The system automatically calculates the calibrated instantaneous flow using the formula:

$$Corrected Instantaneous Flow = A02 (Scale Factor) × Measured Instantaneous Flow − A09 (Offset Flow)$$

A09 Options, RS485 Values, Read/Write Commands, and Formats

Parameter Input Range	RS485 Value
Default	0
Minimum	0
Maximum