Maximum Cable Capacitance; Installation In Conjunction With A Rosemount 333 Hart Tri-Loop Hart-To-Analog Signal Converter - Emerson Fisher FIELDVUE DVC6000 Instruction Manual

START HERE
Unpack the
HART Tri-Loop
Review the HART
Tri-Loop Product
Manual
Digital valve No
controller
Installed?
Yes
Set the digital
valve controller
Burst Option
Set the digital
valve controller
Burst Mode
A
E0365 / IL

Maximum Cable Capacitance

The maximum cable length for HART communication
is limited by the characteristic capacitance of the
cable. Maximum length due to capacitance can be
calculated using the following formulas:
Length(ft) = [160,000 − C
master
Length(m) = [160,000 − C
master
where:
160,000 = a constant derived for FIELDVUE
instruments to ensure that the HART network RC time
constant will be no greater than 65 μs (per the HART
specification).
C = the capacitance of the control system or
master
HART filter
C = the capacitance of the cable used
cable
(see table 2-1)
The following example shows how to calculate the
cable length for a Foxboro
with a C of 50, 000 pF and a Belden 9501 cable
master
with characteristic capacitance of 50pF/ft.
Length(ft) = [160,000 − 50,000pF] [50pF/ft]
Length = 2200 ft.
The HART communication cable length is limited by
the cable characteristic capacitance. To increase
cable length, select a wire with lower capacitance per
foot. Contact your Emerson Process Management
September 2013
Install the HART
Tri-Loop. See
HART Tri-Loop
product manual
Mount the
HART Tri-Loop
to the DIN rail.
Wire the digital
Install the digital
valve controller to
valve controller.
the HART Tri-Loop.
Install Channel 1
wires from HART
Tri-Loop to the
control room.
(Optional) Install
Channel 2 and 3 wires
from HART Tri-Loop
to the control room.
Figure 2-27. HART Tri-Loop Installation Flowchart
(pF)] [C
(pF/ft)]
cable
(pF)] [C
(pF/m)]
cable
t
I/A control system (1988)
A
B
Configure the
HART Tri-Loop
to receive digital
valve controller
burst commands
Pass system
test?
Yes
DONE
B
sales office for specific information relating to your
control system.
Installation in Conjunction with a
Rosemountt 333 HART Tri-Loop
HART-to-Analog Signal Converter
Use the DVC6000 digital valve controller in operation
with a Rosemount 333 HART Tri-Loop
HART-to-Analog Signal Converter to acquire an
independent 4-20 mA analog output signal for the
analog input, travel target, pressure, or travel. The
HART Tri-Loop accepts any three of these digital
signals and converts them into three separate 4-20
mA analog channels.
Refer to figure 2-27 for basic installation information.
Refer to the 333 HART Tri-Loop HART-to-Analog
Signal Converter Product Manual for complete
installation information.
Commissioning the Digital Valve
Controller for use with the HART
Tri-Loop Signal Converter
To prepare the digital valve controller for use with a
333 HART Tri-Loop, you must configure the digital
valve controller to burst mode, and select Burst
Command 3. In burst mode, the digital valve controller
provides digital information to the HART Tri-Loop
Installation
Check
No
troubleshooting
procedures in
HART Tri-Loop
product manual.
2-33
2