Yokogawa EJX930A - Manual (Page 24)

<4. Getting Started>
4-1
IM 01C25R03-01E
4. Getting Started
Fieldbus is fully dependent upon digital
communication protocol and differs in operation
from conventional 4 to 20 mA transmission and the
HART communication protocol. It is recommended
that novice users use field devices in accordance
with the procedures described in this section. The
procedures assume that field devices will be set up
on a bench or in an instrument shop.
4.1 Connection of Devices
The following are required for use with Fieldbus
devices:
• Power supply:
Fieldbus requires a dedicated power supply. It
is recommended that current capacity be well
over the total value of the maximum current
consumed by all devices (including the host).
Conventional DC current cannot be used as is.
• Terminator:
Fieldbus requires two terminators. Refer to
the supplier for details of terminators that are
attached to the host.
• Field devices:
Connect Fieldbus communication type EJX
multivariable transmitter. Two or more EJX
devices or other devices can be connected.
• Host:
Used for accessing field devices. A
dedicated host (such as DCS) is used for
an instrumentation line while dedicated
communication tools are used for experimental
purposes. For operation of the host, refer to
the instruction manual for each host. No other
details on the host are given in this manual.
• Cable:
Used for connecting devices. Refer to “Fieldbus
Technical Information” (TI 38K03A01-01E)
for details of instrumentation cabling. For
laboratory or other experimental use, a twisted
pair cable two to three meters in length with a
cross section of 0.9 mm 2 or more and a cycle
period of within 5 cm (2 inches) may be used.
Termination processing depends on the type of
device being deployed. For EJX multivariable
transmitter, use an M4 screw terminal claw.
Some hosts require a connector.
Refer to Yokogawa when making arrangements to
purchase the recommended equipment.
Connect the devices as shown in Figure 4.1.
Connect the terminators at both ends of the
trunk, with a minimum length of the spur laid for
connection.
The polarity of signal and power must be
maintained.
EJX
Fieldbus power
supply
Terminator
Terminator
HOST
F0401.ai
Figure 4.1 Cabling
SUPPLY
CHECK
PULSE
+
–
+
–
Power supply and output terminal
+
–
PULSE − / CHECK −
PULSE + Communication
terminals
connection hook
RTD cable connection
Check meter
connection hook
SUPPL
Y
PULSE
CHECK
ALARM
SUPPLY +
SUPPLY −
CHECK +
F0404.ai
Ground terminal
Not available for Fieldbus communication
type
Figure 4.2 Terminal Configuration