ABB TTH300 Series Operating Instruction page 27

TTH300 HEAD-MOUNT TEMPERATURE TRANSMITTER | OI/TTH300-EN REV. E
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.
Unless the profile HART protocol Rev. 7 is specifically selected
during the ordering process, the device normally supports the
profile HART protocol Rev. 5 in the delivery status. The user can
later change at any time to the HART Protocol Rev. 7 profile via a
miniature switch. For additional information, see Hardware
settings on page 31.
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
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