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This application note discusses the connection of a Senquip ORB-X1-W to a 4-20mA level sensor that would typically
be used to measure the depth of a water tank or dam.
Connecting the level sensor to an ORB will allow water level data to be delivered to the internet or a remote server
anywhere in the world.
The Sensor being used in this application can measure water in the range 0 to 5m, where 0m is represented by 4mA
and 5m is represented by 20mA.
Hardware Interconnect
The ORB-X1 has two integrated current sources that can be used to drive 4-20mA sensors. The current supplied by
each source is accurately measured and reported. The current sources on the ORB generate their own 12V source,
meaning that the supply to the ORB is not critical. With an input voltage between 9V to 75V or with AA batteries,
the ORB will generate 12V on the current sources. Note that with AA batteries, the measurement interval should be
long to avoid draining the batteries.
Pins 1 and 2 of the ORB should be connected to power and ground. The power in this case is likely to be derived
from a solar panel. If solar is used, measurements can continue to be taken outside of sunlight hours as the ORB has
an internal backup battery. It is recommended that a 1A fuse be inserted between the solar panel and the power
connection of the ORB. The fuse protects the battery in the event that the ORB fails of the positive wire comes
loose. A 10W solar panel will ensure that the internal backup battery remains charged even during extended periods
of cloud.
Since the ORB has two current sources, it can measure two current devices at the same time. In this case however, a
single level sensor is used and it is decided to connect it to source 1. The level sensor should be connected between
source 1 on pin 3 and ground.
App Note:
Connecting to a 4-20mA Level Sensor.
AN003
Typical 4-20mA level sensor
