Yokogawa EJX930A - Manual (Page 8)

<2. Connection>
2-2
IM 01C25R05-01EN
2.1.2 Wiring
(1) Terminal Wriring
Fig 2.1 shows the instruction of terminal wiring
(Power supply and 2-wire RS-485). Power must be
supplied after all wrings are finished.
SUPPLY
MODBUS
+
–
Power supply terminals
Modbus communication (RS-485) terminals
Ground terminal
Terminal Wiring
A
B
F0204.ai
MODBUS B
Communication
terminal
connection hooks
RTD cable connection
SUPPLY +
SUPPLY –
MODBUS A
Figure 2.1 Terminal Wiring
(Power supply and 2-wire RS-485)
(2) Power Supply
The transmitter requires between 9 and 30 V dc
with less than 2% ripple, and sufficient current
capacity.
IMPORTANT
Do not connect power wiring to the
MODBUS(RS-485) terminals. It may damage
EJX Multivariable Transmitter.
NOTE
The EJX Multivariable Transmitter power supply
is not electrically isolated from the RS-485 bus.
(3) Cable
Balanced pairs should be used. AWG 20 or thicker
should be used for over 300 m.
(4) Grounding
Grounding is always required for the proper
operation of transmitters. Refer to IM 01C25R01-
01E “EJX910A and EJX930A Multivariable
Transmitters” Chapter 7.
(5) Multi drop communication
Up to 32 EJX Multivariable Transmitters can be
connected on RS-485 bus. Refer to Figure 2.2 for
Multi drop connection.
A
B
+
– MODBUS
SUPPL
Y A
B
+
– MODBUS
SUPPL
Y A
B
+
– MODBUS
SUPPL
Y
EJX Multivariable
Transmitter*
EJX Multivariable
Transmitter*
EJX Multivariable
Transmitter*
Power Supply
MODBUS
HOST
RS-485 Bus
+
–
A
B
A
B
F0205.ai
*: RS485 bus termination can be selected
by the hardware switch.
Figure 2.2 Multi drop connection