Power Supply - Profibus / Foundation Fieldbus - ABB TTH300 Operating Instruction

28 TTH300 HEAD-MOUNT TEMPERATURE TRANSMITTER | OI/TTH300-EN REV. G
... 8 Electrical connections
... Electrical data for inputs and outputs
Voltage drop on the signal line
When connecting the devices, note the voltage drop on the
signal line. The minimum supply voltage on the transmitter must
not be undershot.
A Transmitter
Figure 18: HART load resistance
U : Minimum supply voltage on the transmitter
1min
U : Minimum supply voltage of the supply isolator /
2min
DCS input
R: Line resistance between transmitter and supply isolator
R : Resistance (250 Ω) for HART functionality
250
Standard application with 4 to 20 mA functionality
When connecting these components, observe the following
condition:
U ≤ U - 22 mA x R
1min 2min
Standard application with HART functionality
Adding resistance R increases the minimum supply voltage
250
U : U ≤ U - 22 mA × (R + R
2min 1min 2min
For HART functionality, use supply isolators or DCS input cards
with a HART mark. If this is not possible, a resistance of ≥ 250 Ω
(< 1100 Ω) must be added to the interconnection.
The signal line can be operated with / without grounding. When
establishing a ground connection (minus side), make sure that
only one side of the terminal is connected to the equipotential
bonding.
For further information on the revision of the standard HART
protocol and on switching options, see HART® Communication
on page 29 and Hardware settings on page 32.
B Supply isolator / DCS input with
supply / segment coupler
)
250
Power supply – PROFIBUS / FOUNDATION Fieldbus
Input terminal voltage
Non-Ex application:
U = 9 to 32 V DC
S
Ex-applications with:
U = 9 to 17 V DC (FISCO)
S
U = 9 to 24 V DC (Fieldbus Entity model I.S.)
S
Current consumption:
≤ 12 mA
Standard application with PROFIBUS PA and FOUNDATION
Fieldbus H1 functionality
During hookup, the following condition should be complied with:
U ≤ U − 12 mA x R
1min 2min