Getting Started; Connection Of Devices - YOKOGAWA digitalYEWFLO Series User Manual

4.

GETTING STARTED

Fieldbus is fully dependent upon digital
communication protocol and differs in operation
from conventional 4 to 20 mA transmission
and the BRAIN communication protocol. It is
recommended that novice users use fieldbus
devices in accordance with the procedures
described in this section. The procedures assume
that fieldbus devices will be set up on a bench or in
an instrument shop.
4.1

Connection of Devices

The following instruments 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. Read the
supplier for details of terminators that are
attached to the host.
• Field devices:
Connect your Fieldbus communication type
digitalYEWFLO to a fieldbus. Two or more
digitalYEWFLOs and other field devices can be
connected. For the terminal assignment on the
digitalYEWFLO, read Table 4.1.
Table 4.1 Terminal Connection for
digitalYEWFLO
Terminal Symbols
SUPPLY +
Fieldbus Communication Signal
Terminals
SUPPLY –
Grounding Terminal
• 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, read the
instruction manual for each host. No other details
on the host are given in this manual.
Description
<4. GETTING STARTED>
• Cable:
Used for connecting devices. Read "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 or more and a cycle period of within
2
5 cm (2 inches) may be used. Termination
processing depends on the type of device being
deployed. For the digitalYEWFLO, use terminal
lugs applicable to M4 screw terminals. Some
hosts require a connector.
Read 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.
Fieldbus power
supply
digitalYEWFLO
Terminator
Figure 4.1 Device Connection
IMPORTANT
Connecting a Fieldbus configuration tool
to a loop with its existing host may cause
communication data scrambling resulting
in a functional disorder or a system failure.
Disconnect the relevant control loop from the bus
if necessary.
4-1
HOST
+ –
Terminator
F0401.ai
IM 01F06F00-01EN