> For the complete documentation index, see [llms.txt](https://iot.datalit.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://iot.datalit.de/appendix/other-sensors/motorized-linear-poti.md).

# Motorized Linear Poti

We can use the [Motorized Linear Poti](https://www.tinkerforge.com/en/doc/Hardware/Bricklets/Motorized_Linear_Poti.html) to let the user control some aspect of our application using a physical control. The poti can take on values on a range between 0 and 100. 

Using the [Tinkerforge Device Manager](/2-internet-of-things/iot-in-our-apps/connect-to-devices/the-tinkerforge-device-manager.md), we can use simple functions to perform the most important tasks. In this article, we assume you have successfully initialized the devices with the [Tinkerforge Device Manager](/2-internet-of-things/iot-in-our-apps/connect-to-devices/the-tinkerforge-device-manager.md), and you stored all connected devices on a global variable `devices`. We also declared a global variable `poti`.

Next, we need to know the device identifier of the Motorized Linear Poti, which is **267**:

```javascript
// Get a reference to the poti device and store in on the global variable
poti = devices.getDeviceByIdentifier(267);
```

Now that we have a reference to the display on the variable `poti`, we can use that variable to call the device's functions.

## Get the updates about the position

In a sense, the Motorized Linear Poti acts like a sensor: We can register a listener to get updates about changes to its position. We first register the listener:

```javascript
poti.registerListener(potiChanged);
```

In the callback function, we can distinguish between two types of updates from the device:

```javascript

function potiChanged(val) {

    // Get the value
    var value = val.getValue():
    
    if(value.type == "position") {
        // Do something
    }
    else if (value.type == "position_reached") {
        // Do something else
    }
}
```

If we are only interested in the position of the poti, regardless of whether it was changed manually or with the motor, we can use the event type `position`. If we are using the motor, as described below, and we want to know when the motor is done moving the slider, we can use the event type `position_reached`. This event is only fired when the motor was used, and it has finished the move.

{% hint style="info" %}
Note that you'll get each position changed using the motor also via the event `position`.
{% endhint %}

## Set the position using the motor

A nice feature of the Motorized Liner Poti is that it has a motor that lets us set the value programmatically:

```javascript
// Set the poti to position 75 using the integrated motor
poti.setPosition(75);
```

The motor moves the slider, which will take a couple of milliseconds. If we want to know when the motor is done, we can check for the "position\_reached" event, as described above.