Rs485 Multi-Drop Connection; Figure 21: Rs485 Multi-Drop Connection; Figure 22: Correct Rs485 Cable Networks; Figure 23: Incorrect Rs485 Cabling - Hydronix Hydro-Probe XT User Manual

Electrical Installation and Communication

3 RS485 multi-drop connection

The RS485 serial interface allows up to 16 sensors to be connected together via a multi-drop
network. Each sensor should be connected using a waterproof junction box.
Do not connect
screen at control
cabinet
From
other
sensors
When designing the cabling for the sensor network, standard installation practices for RS485
networks is that the cable should run in a bus topology rather than as a star topology. This
means that the RS485 cable should run from the control room to the first sensor before linking on
to any other sensors in turn. This is shown in Figure 22.

Figure 21: RS485 multi-drop connection

Figure 22: Correct RS485 cable networks

Figure 23: Incorrect RS485 cabling

A
B
G
Hydro-Probe XT User Guide HD0538 Rev: 1.6.0 29
Chapter 3
0975A twisted
pair Sensor
Cable
Junction
Box
To PC
or plant
F
control
device