
Doc
#
E166703
5-4
5: Communicating with the Meter
Electro
Industries/GaugeTech
The Leader In Power Monitoring and Smart Grid Solutions
Electro
Industries/GaugeTech
The Leader In Power Monitoring and Smart Grid Solutions
Electro
Industries/GaugeTech
The Leader In Power Monitoring and Smart Grid Solutions
Figure 5.4 shows a representation of an RS485 Daisy Chain connection. Refer to
5.1.2.1: Using the Unicom 2500, on page 5-5 for details on RS485 connection for the
Unicom 2500.
Figure 5.4: RS485 Daisy Chain Connection
Figure 5.5: Incorrect “T” and “Star” Topologies
Twisted pair, shielded (SH) cable
R
T
+
-
SH
R
T
+
-
SH
+
-
SH
+
-
SH
Slave device 1
Slave device 2
Last Slave device N
Master device
Earth Connection, preferably at
single location
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
+
-
SH
+
-
SH
+ -
SH
Slave device 1
Slave device 2
Last Slave device N
Master device
Earth Connection, preferably at
single location
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
+
-
SH
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
Twisted pair, shielded (SH) cable
+
-
SH
+
- SH
+
-
SH
+ -
SH
Master device
Slave device 1
Slave device 2
Slave device 3
Slave device 4
R
T
R
T
+
-
SH
Long stub results “T” connection that can cause
interference problem!
“STAR” connection can cause interference
problem!