> For the complete documentation index, see [llms.txt](https://cavedu.gitbook.io/linkit-7697/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cavedu.gitbook.io/linkit-7697/linkit-7697-development-guide-for-arduino-ide/developer-guide/using-mcs-library/connecting-to-mcs.md).
# Connecting to MCS
We use an example to show you how to connect to MCS web service. This example connects to the service with **MCSDevice** class, and allows users to remotely turn on and off the on-board LED of the LinkIt 7697 HDK from MCS web console.
### Create your MCS test device
Visit [MCS web console](https://mcs.mediatek.com/) and create your prototype, data channels and a test device. In this example, you need to create 2 data channels:
1. A **Controller** channel with type **ON/OFF**.
2. A **Display** channel with type **ON/OFF**.
{% hint style="info" %}
If you are not sure how to create prototype, test device and channels, refer to the [MCS Getting Started](http://mcs.mediatek.com/resources/latest/tutorial/getting_started) page.
{% endhint %}
Your test device should look like the screenshot below. Note the **Data channel Id**, **DeviceId**, and **DeviceKey** fields, which we'll be using later.
### Use MCS Library to connect to MCS
To connect to MCS, we need to create a **MCSDevice** object with **device key** and **device ID**, and set the data channels accordingly.
1. In your Arduino IDE, select **File**, then **Examples**, click **MCS** then select **LED\_control**\
2. We'll access MCS through the Wi-Fi network. Modify the Wi-Fi **SSID** and **password** of your Wi-Fi network in the example sketch:
```
// Assign AP ssid/password here
#define _SSID "your_ssid"
#define _KEY "your_password"
```
3. Set the **device ID** and **device key** to the MCSDevice constructor in the sketch:
```
// Assign device id/key of your test device
MCSDevice mcs("your_device_id", "your_device_key");
```
The device ID and device key can be found in the MCS console, as shown below:
4. Assign the channel IDs of your test device:
```
// Assign data channel ID
MCSControllerOnOff led("your_channel1_id");
MCSDisplayOnOff remote("your_channel2_id");
```
The channel IDs can be found in the bottom of the data channel view, as shown below:
### Run the Sketch
1. Click **Upload** and wait for the **Done Uploading** message to appear.
2. Click **Serial Monitor** in the toolbar and adjust the **Baud rate** setting to **9600.**
3. You can now operate the **switch controller** on [MCS web console](https://mcs.mediatek.com/v2console/) to turn on or off the LED light on the development board. It also updates the value back to **switch display channel**.\
4. Please observe the **LED PIN 7** blinking on the development board. The LED light is on and off according to your operation on the [MCS web console](https://mcs.mediatek.com/v2console/).
### Code
In this case, use **MCS library** to deal with the interaction between the physical device and MCS web server. First, include the MCS library.
Create instances of **MCSControllerOnOff** and **MCSDisplayOnOff** class which represent the **switch data channels** you created in the prototype on MCS and provide data channel ID as the parameter.
```
MCSControllerOnOff led("your_channel1_id");
MCSDisplayOnOff remote("your_channel2_id")
```
Associate this physical device to the **test device** on MCS by creating an instance of **MCSDevice** class with device ID and key.
```
MCSDevice mcs("your_device_id", "your_device_key");
```
Attach those data channel instances to the test device and use `connect()` to initialize the TCP connection to MCS server.
```
// setup MCS connection
mcs.addChannel(led);
mcs.addChannel(remote);
while(!mcs.connected())
{
Serial.println("MCS.connect()...");
mcs.connect();
}
```
`Call update()` in the loop() to check if there is new data point received on physical device for **switch controller** data channel. If yes, then assign the new value to **LED\_PIN** setting to either turn on or off the LED.
```
if(led.updated())
{
Serial.print("LED updated, new value = ");
Serial.println(led.value());
digitalWrite(LED_PIN, led.value() ? HIGH : LOW);
if(!remote.set(led.value()))
{
Serial.print("Failed to update remote");
Serial.println(remote.value());
}
}
```
To know more about the MCS library, please refer to MCS Library Usage.