3
DREAM
Interface
2W
RTU
RTU
7
RTU
8
RTU
1
RTU
13
RTU
15
RTU
9
RTU
10
RTU
2
RTU
3
RTU
11
RTU
12
RTU
5
RTU
6
RTU
4
RTU
14
Charger
Battery
+
-
RS485
Remote
I/O
2 wired RTU line
the charger can be
replaced by a
solar panel
THE TWO WIRED SINGLE CABLE SYSTEM OF
THE DREAM
1. SYSTEM OVERVIEW
The DREAM TWO WIRED SINGLE CABLE SYSTEM utilizes
R
emote
T
erminal
U
nits for
connecting remote valves and distant meters to the control system covering territories of up to
10 Km radius by use of 2 wired cables.
The Remote Terminal Units (RTU) have the ability to communicate with the DREAM, to carry
out the received commands and to report back the status of the meters connected to them.
The 2 wired line may handle as many as 60 RTUs. There are two types of RTUs: the
MODULAR RTUs and the COMPACT RTUs.
Each MODULAR RTU can handle up to 8 outputs (in steps of 2,4,6,8),and up to 8 digital
inputs (in steps of 4,8) . Each COMPACT RTU may have 0,1 or 2 outputs and 0,1 or 2 inputs
The outputs activate 2 wired 12v DC pulse latching solenoids. The inputs are dry contacts.
The system is a DC system designed for low power consumption and may be powered by
solar energy.
One DREAM may handle several single cable channels, each channel may contain up to 60
RTUs all of them will be scanned second by second.
1.1
THE PARTS OF THE SYSTEM AND THEIR FUNCTION
The heart of the system is the DREAM control unit that controls the whole system. The two-
wired RTU system is connected to the DREAM by a special interface called 2W RTU
INTERFACE which will be connected through the REMOTE I/O serial communication line
(RS485). The 2W RTU INTERFACE handles both the communication and the energy supply
to all the RTU units. The 2 wired line between the interface and the RTU units goes like
branches of a tree whose root is at the interface and the leaves are the RTUs.
The whole system can be powered either from the mains or by a 20 Watt solar panel using a
rechargeable car battery of 40 Ah or more, for backup. However when the DREAM contains
more than one 2W RTU channel ( more than one 2W interface), the additional 2W channels
will have their own separate power supply/charger and another car battery of 40 Ah or more.
The system will usually have a lightning protection unit installed close to the 2W interface.
When the area is known to be lightning prone, more protection units may be installed in the
field.
