> For the complete documentation index, see [llms.txt](https://mapir.gitbook.io/daq/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mapir.gitbook.io/daq/daq-u/using-multiple-daq-u-together.md).

# Using Multiple DAQ-U Together

Using more than one DAQ sensor on the same computer lets you measure reflectance continuously. You can combine any DAQ models across any transports — for example two DAQ-U over USB-C, or a DAQ-U reading an object while a DAQ-M (Bluetooth) or DAQ-E (Ethernet) reads the ambient light.

## Measuring Reflectance

You can measure an object's reflectance by using two or more DAQ sensors: one measures the ambient (downwelling) light while the other measures the light reflected from the object. Because the ambient reference is measured continuously, the calibration updates automatically as the light changes, and you do **not** need to scan a reference reflectance calibration target between measurements.

Point the ambient sensor upward with the **Sunshine cap** to capture downwelling light, and fit the object sensor with a **field-of-view cap** so it reads only the target.

Using the Chloros CLI, a two-sensor reflectance measurement looks like this:

```
chloros-cli daq reflectance --ambient-port COM3 --object-port COM4 -d 60
```

Add `--record` to save the object stream to a `.daq` file. See [Capturing Light Sensor Data](/daq/daq-u/capturing-light-sensor-data.md) to set up each sensor.

{% hint style="info" %}
For every ambient / object sensor combination and the full set of reflectance options, see the Chloros Manual at [docs.chloros.com](https://docs.chloros.com) *(link coming soon)*.
{% endhint %}