The DW 918 N is a wireless industrial GPRS data transfer device which performs router functions. It is for use in systems requiring wireless data communications with outstandingly high availability, parallel redundant data connections, and IPSec encryption.

Application

The DW 918 N industrial router is used as a field wireless communication device in industrial communication systems where high reliability is required. The device, in cooperation with the 918LC central router and using the IPSec protocol, creates a reliable data connection between field devices and a central process control system. The optional GPRS redundancy is realized by switching to a backup service provider’s system if the GPRS system of the preferred provider behaves abnormally.

The easy and secure connection to the field and central networks is made possible by the NAT function of the DW 918 LC and DW 918 N routers.

Settings

Operational parameters and settings can be adjusted via an integrated web server and the HTML page it presents and also via the engineering port (12C bus) using the DW 900 TWI software.

Operation

The operation of the device fundamentally corresponds to that of a traditional router. When specifying target IP addresses always that of a single DW918 LC unit SIM card is given (static route table).

The target IP addresses must be accessible from the APN used by the DW 918 N iGPRS device. In the case of dynamic routing, the route table is automatically filled in according to the current IP traffic.

During operation a continuous GPRS connection is ensured and when necessary makes use of the alternative GSM provider. (SIM redundancy).

While routing, the device handles every IP packet which meets the given routing rules. When necessary NAT-ing is used and as such only ICMP, UDP, and TCP packets are allowed to pass.

When NAT-ing the device replaces the target IP address in the IP packet header with an address falling in another range. In the reverse direction the original IP address is restored. With this solution, the injection of virtual IP addresses (address ranges) into the network becomes possible.