Digital Communications; Grounding - ABB LST100 Operating Instructions Manual

3.2.3 Digital communications

The LST100 is configured using RS485 digital
communications. The RS485 connection is made
to the terminals shown in Fig. 3.4.
Fig. 3.4: RS485 communication terminals
The LST100 uses RS485 for digital communication. RS485
is an asynchronous, half duplex communication method
that can transmit measurement results and alarm information
from the LST100, and configuration and control commands
to the LST100. The length of the cable used for digital
communication is limited by the communication baud rate
and FM approval requirements.
– The LST100 transmitter's RS485 port is designed for
point-to-point communication and does not support
network topology.
– The baud rate of the LST100 transmitter's RS485
communication is fixed at 9600 bps.
– The LST100 supports cable lengths of up to 30 m (100 ft).
–
RS485
+

3.2.4 Grounding

The LST100 requires a ground connection
to the terminal shown in Fig. 3.5.
Fig. 3.5: The ground connection terminal
The LST100 provides one connector for ground (PE).
An effective ground connection is needed for optimum
EMC protection. The shielding of a shielded cable can
be used for grounding.
All grounding must comply with anti-explosion regulations
if the LST100 transmitter is to be used in hazardous
environments (Zone 1 or Div 1 and Zone 2 or Div 2).
LST100 – Ultrasonic level transmitter | OI/LST100-EN 11
Ground (earth)