Description

Since the EM300-CL works by calculating the level change through the change of inductive capacitance of the liquid, but in the actual use scenario, the use of different bottles and liquids may produce different inductive capacitance, it is recommended that running a calibration of the EM300-CL before installing the device. This article describes how to calibrate the EM300-CL using the Toolbox APP.

Requirement

• EM300-CL with firmware version 1.2 and above
• Toolbox APP with v2.0.1 and above

Configuration

Step 1: 

To quickly perform manual calibration, please change the reporting interval and collecting interval of the EM300-CL to 1 minute via Toolbox APP first. After calibration, you can change the intervals to suit your actual usage scenario.

Note: If the measured liquid is viscous and adheres to the bottle surface, such as hand sanitizer or oil, you need to wait for the liquid to settle completely before continuing with the calibration steps.

Step 2:

First confirm that the probe is secured to the container.

When the height of the measured liquid is in the middle of the probe of the EM300-CL. Wait one minute and confirm the current value of ∆C' using the toolbox reading.

Please refer to the following example, when the liquid height reaches the middle position of the probe, the current value of ∆C' is 216.

Liquid level:

∆C value:

Step 3:

When the height of the measured liquid exceeds the probe, wait one minute and use the toolbox to read the current value of ∆C.

According to the example, when the liquid exceeds the probe, the current value of ∆C is 64.

Liquid level:

∆C' value:

Step 4:

At this point, click 'Calibrate' and write to EM300-CL.

Step 5:

When the liquid level reaches the center of the probe, the device determines that this is a state of liquid shortage.

By calculating |∆C-∆C'| ,  we can confirm the trigger value from full liquid level to the lack of liquid.

In this case, |∆C-∆C'| =|64-216| = 152,  so we can determine 152 as the trigger value for going from full liquid to lack of liquid. Write 152 into the full liquid judgment value.

In addition, considering that there may be some tolerance in the actual measurement process, we recommend reserving some redundancy when setting the judgment value and setting a slightly larger judgment value.

For example, in this example, the calculated value is 152, then +1 can be added to 152 as the judgment value.

Note:

After completing the manual calibration steps, please add or reduce the measured liquid so that the height is above or below the probe, and observe whether the liquid level changes correctly. 

The process of addling liquid needs to be gradual, transitioning from above the probe, to the middle of the probe, and then below the probe. The entire process should take at least one minute; in other words, do not immediately change the liquid height from above the probe to below the probe. The EM300-CL can only detect gradual changes in liquid height.

Test Example after Calibration

Check the reported status of the sensor via packets from network server.

1 indicates that the liquid level is higher than the probe. 

2 indicates that the liquid inside the bottle is almost used up, with the liquid level at or below the middle position of the probe.

Full:

Critical Liquid Level Alert: