Volume 8 – Mechanical and Electrical Services - Malaysia Geoportal

Chapter 10 SCADA AND AUTOMATION SYSTEM
e) Ethernet
Ethernet, especially ethernet LAN has always been chosen for communication between local
controller (for example in between RTU (Remote Terminal Unit) and PLC (Programmable
Logic Controller)) due to its speed and reliability. Sometime, it is also used to communicate
between RTU and web cam at site.
f) Wireless Radio
Radio communication is one of the oldest communication method in SCADA communication.
Radio can be used in both short distance and long distance communication. Anyway, due to
reliability issue especially interference during bad weather, radio communication had became
less popular communication method as more and more reliable new wireless communication
method in market.
g) Wireless LAN
Wireless LAN communication is one of the most popular and reliable communication for short
and medium distance communication method. Example of successful implementation case
can be found in S18, Penang Urban Drainage Pump Expert system where wireless LAN
communication link up trash screen and Pump house with distance more than 100m.
Another example in PA (Pintu Air) Sg Klebang, Melaka where wireless LAN link up 2 units of
PTZ Web Cam with RTU.
Communication method for Long distance communication implemented including:
a) PSTN (Public Switched Telephone Network)
PSTN is one of most conventional communication method implemented in SCADA
communication due to ability and cost effective. Anyway, after few years implementation in
DID SCADA communication, DID discovers that most of the PSTN communication faces
surging problem, especially for lightning surge.
b) GSM
Global System for Mobile communications (GSM) is the most popular standard for mobile
phone in the world. GSM is used by over 2 billion people across more than 212 countries and
territories. Implementation of GSM communication in SCADA communication is very similar
to PSTN communication where communication only happened in one to one method with
communication Modem. Thus, most of the SCADA system in DID still implement GSM for
remote control due to security purpose.
c) GPRS
General Packet Radio Service (GPRS) is a Mobile Data Service available to users of Global
System for Mobile Communications (GSM) and IS-136 mobile phones. GPRS data transfer is
typically charged per kilobyte of transferred data, while data communication via traditional
circuit switching is billed per minute of connection time, independent of whether the user
has actually transferred data or has been in an idle state. Popular communication method to
transfer the data from RTU to Server through internet. (Even 3G is better than GPRS, but
availability of 3G in Malaysia is limited.)
March 2009 10-13