GE Grid Solutions Multilin 9450 - Rs485 Connection; Connection to an Rs485 Master

CHAPTER 5: COMMUNICATION WIRING RS485 COMMUNICATION
EPM 9450/9650 ADVANCED POWER QUALITY METERING SYSTEM – INSTRUCTION MANUAL 5–7
Figure 5-6: Incorrect “T” and “Star” Topologies
5.3.1 RS485 Connection
• Use any Port on the EPM 9450/9650 meter. If you use Port 1, set the selector switch
beneath the port to RS485.
• The link using RS485 is viable for up to 4000 feet (1219 meters).
• You must use an RS485 to RS232 converter.
• For information on connecting the EPM 9450/9650 meter to a modem, see
sections 5.8.2 and 5.8.3.
• Do not use the V(+)/V(-) pins: they supply power to the EPM displays and I/O
modules.
5.3.2 Connection to an RS485 Master
• To establish communication between a EPM 9450/9650 meter and any RS485
master or RS232/RS485 converter, use a shielded, twisted pair cable.
• Use an RS485 port (Ports 1–4) on the EPM meter. If you use Port 1, set the selector
switch beneath it to RS485. Connect the (+) and (-) terminals on the meter to the (+)
and (-) terminals on the master. Provide jumpers on the master, linking its two (-)
terminals and two (+) terminals. RS485 communication is viable for up to 4000 feet
(1219 meters).
Twisted pair, shielded (SH) cable
+ - SH
+ - SH
+ - SH
Slave device 1
Slave device 2
Last Slave device N Master device
Earth Connection, preferably at
sin
g
le 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
p
roblem!
“STAR” connection can cause interference
p
roblem!