Architecture; Using Active Opc Server To Resolve Dynamic Ip Addresses - Moxa Technologies ioLogik W5300 Series User Manual

ioLogik W5300

Architecture

Cellular networks usually run in a dynamic IP environment with private IP addresses assigned by the cellular
service provider. To allow private networks to get around the connectivity issues raised by edge devices
configured with dynamically assigned private IP addresses, typically operators purchase high-cost static IP
addresses for each device, with IPs provided by a DDNS or VPN service purchased from an MVNO (Mobile
Virtual Network Operator). Even with DDNS technology, SCADA systems need to assign resources to manage
the DDNS servers. As an alternative, Moxa's Cellular remote I/O devices use Moxa's proprietary "push"
technology, called Active OPC Server. With Moxa's powerful Active OPC Server support, communications
efficiency between ioLogik W5300 devices and the central SCADA are substantially improved. Moxa's Active
OPC Server's non-polling communications architecture supports the standard OPC protocol, but instead of
requiring the SCADA to poll edge devices it allows edge devices to actively push communications to the central
HMI/SCADA system, empowering the network with real time I/O updates while substantially cutting network
overhead.
Unlike the requirements of a traditional OPC server (where remote I/O devices must use a static IP so they may
be successfully polled), Active OPC Server and ioLogik products allow engineers the flexibility of configuring
edge devices with dynamic IP addresses. Even when using DHCP addressing, ioLogik devices can push
messages back to the OPC server, allowing wide area I/O networks using dynamic IP cellular accounts. Using
traditional polling OPC applications, I/O devices cannot make use of this approach.

Using Active OPC Server to Resolve Dynamic IP Addresses

With its push communications capabilities, Active OPC Server can be configured to become a cellular gateway
that enables direct communications from the edge back to the core. By configuring the Active OPC Server with
a static address, remote I/O devices may push their IP addresses back to the OPC server and thus register with
the SCADA over a cellular network. In this way, edge devices can communicate their new IP address directly,
easily sidestepping dynamic IP addressing issues. The topology is illustrated below:
1-2
Introduction