Installation
2.3.4 Analog input
The WL-TX-900 module provides one 0 - 20 mA analog input for connecting to
instrument transducers (e.g. level, moisture, pressure transducers, etc.).
The WL-TX-900 module inputs measure down to 0mA and can also be used for zero
based signals (e.g. 0 - 10 mA). The analog input has a positive and negative terminal
and can be placed at any point in the current loop, providing neither input rises above
the 24 volt Analog Loop Supply level.
Each input has a loop resistance of less than 250 ohms and zener diode protection is
provided against over-voltage and reverse voltage.
A 24VDC loop supply is available on the WL-TX-900 module for powering the analog
transducer loops. In this situation, connect the:
Analog loop - between an Analog Input (-) terminal and Ground.
Positive terminal – i.e. Analog Input (+) to the +24V Analog Loop Supply.
Externally powered loops may be connected by connecting the input between "Analog
Input (+)" and “Analog Input (-)”
Common mode voltage may be -0.5V to 27V. Signal Isolators are recommended for
systems with higher common mode voltages (typically high voltage or noisy
environments or for long wiring runs).
For effective protection from electromagnetic noise, all signal cables must be shielded,
or located on conductive trays or in conduits.
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