Yokogawa EJX115A - Manual (Page 13)

<2. Connection>
2-4
IM 01C25T01-06EN
2.5 Interconnection Between
DPharp and the HART
Configuration Tool
The HART configuration tool can interface with the
transmitter from the control room, the transmitter
site, or any other wiring termination point in the
loop, provided there is a minimum of 250 Ω
between the connection and the power supply. To
communicate, it must be connected in parallel with
the transmitter; the connections are non-polarized.
Figure 2.2 illustrates the wiring connections for
direct interface at the transmitter site for the
DPharp. The HART configuration tool can be used
for remote access from any terminal strip as well.
USB
FieldMate
Modem
Relaying
terminals Distributor
Control room
Terminal
board
F0202.ai
USB
PC/FieldMate
HART configuration tool
DPharp
SUPPL Y
PULSE
CHECK ALARM
Figure 2.2 Connecting the HART Configuration
Tool
2.6 Power Supply Voltage and
Load Resistance
When configuring the loop, make sure that the
external load resistance is within the range in the
figure below.
(Note) With an intrinsically safe transmitter, external load
resistance includes safety barrier resistance.
600
250
0 10.5 16.6 25.2 42
External
load
resistance
R (Ω)
Power supply voltage E (V DC)
F0203.ai
Communication
applicable range
R= E–10.5
0.0244
Figure 2.3 Relationship between Power Supply
Voltage and External Load Resistance