Implementation guide for connecting a AN420 water level sensor to a C-Bus system

Overview
The AN420 water level sensor is a 4-20mA device that is very easy to connect to C-Bus systems via the C-Bus General Input Module (CBGIM).  4-20mA is a industry standard method of connecting sensors and devices to monitoring equipment. 

The AN420 4-20mA sensor has the following advantages:

• 4-20mA current loop is immune to induced electrical noise. This means that the AN420 sensor cable can share conduits that carry power or other signals.

• 4-20mA sensor cable can be extended to well over 1000m.

• The AN420 is connected to the C-Bus GIM via a 2 core cable that carries both power and signals to and from the sensor. This makes for easy and a low cost connection.

• The AN420 may be powered by a DC voltage source that ranges from 10 to 36V. The C-Bus GIM has a 24V power source that powers the AN420.

• The Anadex C-Bus Scaling Calculator for AN420-5 or C-Bus Scaling Calculator for AN420-15 can be used to easily calculate required scaling factors to map the raw sensor signals to real world values such as liters, percentage or depth.

• AN420 water level probe
• C-Bus General Input Module

Installation and configuration

Install the C-Bus GIM.
Connect the AN420 to one of the 4 channels on The C-Bus GIM.
Note that the General Input Unit Software has a Connect Button that will display a connection diagram for a 4-20mA device if required.
Connect the RED conductor to the 24VDC OUT terminal block.
Connect the BLACK conductor to the terminal block marked A on one of the GIM channels.
Place a jumper between the A terminal and the terminal next to it that has a number. (1,2,3 or 4).
If you are using the first channel, then you would connect the Black conductor to the A terminal and jumper the A terminal to the terminal marked 1.

Using the Clipsal General Input Unit software, go to the Channel programming screen and configure the channel to accept signals from the AN420 sensor.
You will have to input values into the following fields:

Description - Enter descriptive text to describe this channel.
This description will only be stored on your computer and not in the CBGIM.
Units - Select Amps.
Unit Multiplier - Select Milli.
Input type - Select 4-20mA
Click on the Connect button to get the connection diagram for connecting 4-20mA sensors to the C-Bus GIM
Scaling - Use the Anadex C-Bus Scaling Calculator for AN420-5  or  C-Bus Scaling Calculator for AN420-15 to calculate the multiplier and offset to be used.
The scaling is used to convert the raw sensor current signal in mA to a Real World value. Use the "Real World" value to display a text value to the user or output to a graph.

Complete the rest of the fields required by your site"s particular requirements.

Installing the AN420 water level probe
Install the AN420 into the tank so that the sensor is located at the bottom of the tank. This may be done by suspending the sensor into the tank. The orientation of the sensor is not important. For optimum performance, the sensor should be installed in such a way that it is just clear of the bottom. This ensures that its performance will not be impeded by sediment that may accumulate at the bottom of the tank.
If you need to extend that sensor cable, then any two core cable may be used to connect to the sensor cable.
Note: Do not block the end of the sensor cable.
The end of the sensor cable must be vented to atmosphere. Use the vented Aquameta junction box to facilitate the connection. The junction box ensures that the sensor cable remains vented and provides a easy way of connecting the extension cable.