VEGA VEGAPULS 45 4 … 20 mA; HART compact sensor - Manual (Page 35)

VEGAPULS 42, 44 and 45 – 4 … 20 mA 35
2 2
4 … 20 mA
4
2
2
Measuring system with VEGAPULS 42 or 44 on active PLC
• Two-wire technology, power supply from active PLC.
• Output signal 4 … 20 mA (passive).
• Measured value display integrated in the sensor.
• Optional external indicating instrument (can be mounted up to 25 m away from the sensor in
Ex area).
• Adjustment with PC, HART ® handheld or the adjustment module MINICOM (can be plugged
into the sensor or into the external indication instrument).
HART ® handheld
VEGA-
CONNECT 2
Electrical connection
1) If the resistance of the processing systems
connected to the 4 … 20 mA signal output is less
than 250
Ω, a resistor must be connected to the
connection cable during adjustment to get a loop
resistance of 250
Ω.
The digital adjustment signal would otherwise be
severely damped or short-circuited due to
insufficient resistance of the connected processing
system. Digital communication with the PC would
not be ensured.
1 )
VEGADIS 50
passive 2)
PLC (active) 3)
2) 4 … 20 mA passive means that the sensor
consumes a level-dependent current of
4 … 20 mA. The sensor reacts electrically like a
varying resistor (consumer) to the PLC.
3) Active means that the PLC powers the passive
sensor as voltage source.