Multiple Sensors Connected To The Sdi-12 Bus - Adcon A725 addSDI User Manual

18
CHAPTER 3
Performing Advanced Functions

Multiple Sensors connected to the SDI-12 bus

GND
1
Detection
Jumper
2
SDI Sense 3
SDI POWER
green
Figure 12. Single Sensor Connection, for sensor with internal battery
Multiple sensors can be connected to the SDI-12 bus as long as
the following conditions are met:
the maximum total (!) current consumption (500mA) is not
•
exceeded
• the maximum number of sensor values (20) is not exceeded
• all sensors have unique addresses
WARNING If two sensors with identical addresses are connected
to the same bus, communication with these sensors is not possible.
Note: The factory default address of most SDI-12 sensors is usually
0. Please use an appropriate tool, usually delivered by the
sensor manufacturer, to change the address. The A725
addSDI RTU is not capable of changing addresses of SDI-12
sensors.
The sensors can be connected in a star, daisy chain or mixed topol-
ogy. Self powered and RTU powered sensors can also be mixed.
See Figure 13 for details.
SDI GND
5
4
SDI DATA
gray
yellow
pack
SDI GND
SDI DATA
SDI−12 SENSOR
self powered