To configure communication failure alerts, go through the following steps:  

Step 1: Select the sensor you want to configure the communication failure alert.

There are three ways to do this:
1- Select the sensor widget from the Sensor tab of your Dashboard.
2- In the main menu, on the left side, click on Locations and Equipment, select Locations and the find the desired sensor in your organization structure.
3- In the main menu, on the left side, click Settings, select Monitoring, then find and click on the sensor

Step 2: A side window will open (Sensor View). Select the General tab.

Step 3: In the Communication failure card you may:

1. Enable/disable the communication failure alert - use the switch button
2. Define how much time after detecting a communication failure will the system send alert.
3. Define the users to be alerted about the communication failure - click on (+) button.

Step 4: After applying the desired configurations click on Save.

Example of the procedure: