PPP Router (Point-to-Point Protocol)

Telecommunications structures used in large-area plants typically provide communication in remote areas with RTUs (Remote Terminal Unit) via serial MODEMs.

The DF125 is designed to be connected between the MODEM's serial interface and the RTU's ethernet local area network (LAN), providing PPP (Point-to-Point Protocol) router functionality that allows IP connectivity of the RTUs to the MTU (Main Terminal Unit).

To accomplish this, via AT commands through the serial port, the DF125 configures and requests the MODEM to establish a PPP connection with a server in the MTU. From then on, all protocols used by Smar RTU can be encapsulated via serial PPP protocol and transmitted via telecommunications structure.


Main Features

  • PPP over the serial port
  • IP address translation
  • Webserver configuration
  • Low power consumption
  • DFI302 modular design


PPP Router Module - DF125


The DF125 is a key element to connect the Smar RTU infrastructure with the telecommunications system used in large plants, enabling serial PPP encapsulation of all protocols used by Smar RTU.

In wide area plants the control system is usually divided into a Main Terminal Unit, a Telecommunications System and several Remote Terminal Units, aiming at standalone and local process intervention, in addition to its simple monitoring.

The RTU’s are normally used as standalone equipment and implemented to perform local control for immediate action upon abnormal process behavior at low power and high connectivity.

The telecom system is the important solution to address the long distances issue introduced by such applications. Various scenarios are known and implemented in different locations, e.g. satellite communication, fiber optics, radio network, GSM/GPRS, 3G, Tetra, etc.

Finally, the MTU is the concentrator of all data coming from different RTUs via telecom and compiled into a single database. The MTU is also implemented to operate, configure, and maintain all RTUs remotely based on various protocols.

Standard OPC and Foundation Fieldbus High Speed Ethernet (FF HSE) communication protocols are used to provide all means to send/receive data to/from RTUs.

In the case of narrowed network bandwidths, specific protocols can also be implemented, such as DNP3 which will target data collection from RTUs where the network cannot be accessed 100% of the time in a shared environment (supervision, control, and voice).


System overview using MTU, RTU and DF125

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