Technical information

3/233/23

Presentation (continued)

Modicon M340 automation

platform

RTU communication protocols

Processors:

page 1/2

I/O:

pages 2/2 and 2/14

Software:

page 4/2

Ruggedized Modicon M340 modules:

page 6/2

Presentation (continued)

Currently, people working in the industrial Telemetry sectors use standard protocols

for communication between control centres (SCADA) and RTU stations.

The most commonly used protocols are as follows:

IEC 60870-5: IEC (International Electrotechnical Commission), in particular IEC

60870-5-101/104 (commonly known as IEC 101 or 104)

DNP3: Distributed Network Protocol version 3

DNP3 is the predominant protocol in North America, Australia and South Africa

whereas, in certain European countries, the IEC protocol is required by the legislation.

IEC is also commonly used in the Middle East.

The geographical distribution of these protocols is as follows:

DNP3: North America, Australia, New Zealand, UK, etc, Asia,

South America

IEC 60870-5: Europe, Middle East, etc, Asia, South America

These protocols offer similar functions.

They are both particularly suited to “transient communications” (modem, radio) and

data exchanges with limited bandwidth for the following reasons:

They transfer data in a very robust and reliable manner between the SCADA

system and the RTU devices

They are essentially “event-triggered” protocols (exchanges on changes of state,

exchanges of time and date stamped events).

They offer the following transmission modes:

Interrogation via polling

Data exchanges on changes of state (RBE: Report By Exception)

Unsolicited messaging (a slave station can start an exchange of data with the

master station).

Both protocols offer native data management and time and date stamped events:

Time synchronization between the master station and auxiliary stations via

protocol functions

Time and date stamping of data and events

Automatic transfer of time and date stamped events between the RTU stations

and SCADA (control room).