ABB LWT300 series, User Manual, Page: 32 / 108

28
User Guide
Connecting the instrument
WARNING
All connections must be established in a de-energized state. Before working on the circuit,
secure the breaker to prevent any accidental power-up.
In an explosion proof/flameproof installation,
do not remove the covers while the
instrument is energized.
ELECTROSTATIC DISCHARGES
Electronic components are sensitive to electrostatic discharges.
Before performing any connection, operators shall make sure that they have discharged all
static electricity from their body before touching electronic components.
NOTICE
Ensure that a drip loop
1
(water trap) is used when installing the connecting cables for
the sensor. If necessary, rotate the transmitter housing as necessary.
—
Figure 19
Typical LWT Modbus connection
Modbus®
Master
Device
Power supply
10.5 to 28.5 V DC
LWT Modbus®
Instrument
A (+)
B (–)
PWR
+
–
A (+)
B (–)
+
–
GND
RS-485
Communication
Link