User's Manual

LX-80 User Manual
Page 9 of 32
3.4. Analog 4 – 20 mA output
Analog current 4 – 20 mA output is provided for easier compatibility with older
logging and control systems. Output is implemented as current sink architecture with
common ground. Maximal voltage applied to the sink can go up to 30 VDC providing
greater flexibility in connection of the sensor to PLCs, loggers, or data concentrators.
Signal range and function for 4 – 20 mA analog output can be configured in setup
application so the sensor will be able to signal best suitable value range with available
current range. Current step in the sensor is 0,3 µA limiting resolution possible for the
value signaling and care has to be taken in the setup of minimal value to be represented
by 4 mA and maximal value to be represented by 20 mA, so the resolution is sufficient
for the system requirements.
3.5. SDI-12 Interface
SDI-12 interface is widely used communication interface in hydrology applications.
Such interface is characterized with only one communication wire, slow speed
communication and possibility for very long communication cables.
For hydrological applications SDI-12 communication interface is possible as option
and instrument is natively able to communicate directly with SDI-12 receivers. The device
is not an SDI-12 slave, it just responds to SDI-12 commands as expected from an SDI-
12 slave. It does not support low power mode and does not go to sleep or wakes up, it
works continuously. Future revision is possible to fully support sleep and wake up. The
device supports SDI 1.3.