Loop-powered display unit
Wiring
17
The HART
®
communication resistance of 230 Ω in the signal line is always
necessary in the case of a low-impedance power supply. It must be installed
between the power supply and the display unit.
Circuit diagram / Description
2-wire sensor with
process display unit and
loop power supply,
without backlighting
Y
I
R
s
DC
1
2
3
LED
-
+
A0019567
1
Sensor
2
Power supply
3
HART
®
resistance
2-wire sensor with
process display unit and
loop power supply, with
backlighting
Y
I
R
s
DC
1
2
3
LED
-
+
A0019568
1
Sensor
2
Power supply
3
HART
®
resistance
4-wire sensor with
process display unit and
loop power supply,
without backlighting
1
3
Y
I
2
4
LED
-
+
A0019570
1
HART
®
resistance
2
Current meter (optional)
3
Sensor
4
Power supply 4-wire device
