Siemens SITRANS FC720 Operating Instructions Manual page 75

Electrical interfaces
For HART communication devices, it is supplied on the current output lout1. The current
output may be operated in compliance with the NAMUR NE43 standard.
Nominal output current
Maximum output current range
Load resistance
Load resistance for secure HART communication
SITRANS FC
Fig. 29: Active current output connection lout HART
①
Passive current
output lout
Nominal output current
Maximum output current range
External power supply
Load resistance for secure HART
communication
Load resistance at current output
Fig. 30: Maximum load resistance as a function of an external power supply voltage
R
U
The diagram shows the maximum load resistance R as a function of voltage U of the
connected voltage source. Higher load resistances are allowed with higher power supply
values. The usable zone for passive power output operation is indicated by the hatched
area.
SITRANS FC
Fig. 31: Passive current output connection lout
Iout+
Iout-
Receiver
911
U - 10.5 V
R =
0.0236 A
0
10.5
U in V
Load resistance
External power supply voltage
Iout+
Iout-
1
Value
4 – 20 mA
2.4 – 21.6 mA
10.5 – 32 V
DC
230 – 600 Ω
≤ 911 Ω
32
U
R
A5E52748387-AA, 2023/09
FC7x0
Transmitter
Value
4 – 20 mA
2.4 – 21.6 mA
≤ 750 Ω
230 – 600 Ω
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