Digi ConnectPort X4 User's Guide download pdf (Page 164)

Configuration through the web interface

164

Connection settings

The Connection settings configure how the Device Cloud-registered device connects to Device

Cloud. These settings include information about communication between the Device Cloud-

registered device and Device Cloud, and the connection methods used by the various interfaces on

the device.

About device-initiated, server-initiated, and paged Device Cloud connections

You can choose how your Device Cloud-registered device connects to and communicates with

Device Cloud: through a device-initiated Device Cloud connection, a server-initiated Device

Cloud connection or a (device-initiated) timed connection. If Short Message Service (SMS)

capabilities are enabled on your Device Cloud-registered device, a paged connection is another

means by which a device-initiated connection may be requested. To illustrate how these types of

connections work, here is a configuration scenario featuring Device Cloud-registered devices

communicating over a cellular network.

Addresses for Device Cloud-registered devices can be publicly known, or private and dynamic, or

handled through Network Address Translation (NAT). NAT reduces the need for a large amount of

publicly known IP addresses by creating a separation between publicly known and privately

known IP addresses. NAT allows a single device, such as a router, to act as an agent between a

public network, such as the Internet or a wireless network, and a private, or local, network. This

means that only one unique IP address is needed to represent an entire group of computers.

Addresses handled through NAT can access the rest of “the world,” but “the world” cannot access

them.

In a device-initiated Device Cloud connection, the Device Cloud-registered device attempts to

connect to the network, and will continue attempts to reach Device Cloud to establish the

connection. To maintain the connection, the Device Cloud-registered device sends keep-alive

messages over the connection. The frequency with which keep-alive messages are sent is

configurable. An advantage of device--initiated Device Cloud connections is that they can be used

in any cellular network, whether public or private IP addresses are used, or even if NAT is used. A

disadvantage is that there can be a charge for the Device Cloud-registered device sending the keep-

alives, depending on cellular/mobile service plan.

A server-initiated Device Cloud connection works the opposite way. Device Cloud opens a TCP

connection, and the Device Cloud-registered device must be listening for the connection from

Device Cloud to occur. An advantage of server-initiated Device Cloud connections is that you are

not charged for sending the keep-alive bytes that are used in device-initiated connections. A

disadvantage is that there is no way of knowing whether the devices displayed in the Device

Cloud-registered device list are offline or connected. The device list shows all the devices as

disconnected until Device Cloud does something to interact with them. In addition, Device Cloud

connections cannot be used for devices that Digi device private IP addresses and are behind a NAT.

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Digi ConnectPort X4 User's Guide Page 164