Electrical connections
24 - EN
TTF300
CI/TTF300-X1
s
4.5.2 HART
functionality
Panel
Control
room
A
B
+
-
U
M
+
U
S
-
R
Ltg
A00095
R
250
Fig. 14
A Transmitter
B Supply isolator / PCS input with supply
Adding resistance R
250
increases the minimum supply voltage:
U
Mmin
U
Smin
+ 0.022 A x (R
Ltg
+ R
250
)
Where
U
Mmin
:
Minimum operating voltage of transmitter
U
Smin
:
Minimum supply voltage of supply isolator / PCS input
R
Ltg
:
Line resistance between transmitter and supply isolator
R
250
:
Resistance of resistor for HART functionality
For HART functionality, use supply isolators or PCS input cards with a HART mark. If this is not
possible, a
250
Ω
(< 1100
Ω
) resistor must be added to the interconnection.
The signal line can be operated with or without grounding. When establishing a ground
connection (minus side), make sure that only one side of the terminal is connected to the
equipotential bonding.
s
4.5.3 PROFIBUS PA and FOUNDATION Fieldbus H1 functionality
Panel
Control
room
A
B
+
-
U
M
+
U
S
-
R
Ltg
A00094
Fig. 15
A Transmitter
B Segment coupler
When connecting these components, observe the following condition:
U
Mmin
U
Smin
+ 0.012 A x R
Ltg
Where
U
Mmin
:
Minimum operating voltage of transmitter
U
Smin
:
Minimum supply voltage of supply isolator / PCS input
R
Ltg
:
Line resistance between transmitter and supply isolator
