Indicates to the imp whether or not it is currently connected to the server
This method is typically used when the imp is operating on a RETURN_ON_ERROR disconnection policy in order to check whether the device is connected. If it is not, the code will first need to call server.connect before it can interact with the server and its agent.
To be connected, the device’s WiFi must be enabled and a TCP socket established with the server.
If the device receives no network traffic from the server for a period of around 60 seconds, it will try to elicit a response from the server (a ‘keepalive’). Calls to server.isconnected() will continue to return
true during this period. If no acknowledgement is forthcoming within approximately 45 seconds, the device will close the socket and record the server as being unavailable, and server.isconnected() will return
This example will tell the user whether or not the device is currently connected to the server when a button is pressed. If the device is connected, a green LED will come on. If the device is disconnected, a red LED will light.