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Model: EC420

The eGauge 4-20mA Sensor is used in conjunction with the Sensor Hub and an EG4xxx model meter (Core or Pro) to read a 4-20mA current loop sensor such as pressure sensors, water level sensors, temperature probes, and other industrial sensors that output a 4-20mA current loop.

Prerequisites: 

• Necessary hardware (not included):
  • EG4xxx or newer eGauge meter
  • eGauge Sensor Hub (ESH044)

Important Installation Notes

• Signal input: Accepts 4-20mA, current levels outside of this range or voltage signals are not compatible.
• Only use straight-through RJ11 cables to connect powered sensors to the Sensor Hub. See this article for more information on verifying the correct RJ-11 wiring. 
• It is not advisable to extend the RJ11 leads from the Sensor to Sensor Hub. It is acceptable to use a longer RJ45 cable from the Sensor Hub to the eGauge.
• If RJ11 cable between Sensor and Sensor Hub must be extended, it is advisable to use twisted pair wires, such as a CAT5 cable with RJ11 plugs (most commonly used for DSL modems).
• If terminating own cables, RJ11 cables should be straight-through cables, with the same color order on both ends. RJ-45 cable should be wired to T-568B as shown on the Sensor Hub.

Instructions: 

Before beginning, check that you have all of the included parts:

Step 1: Connect the EC420 Sensor to an available RJ11 port on your Sensor Hub using the included RJ11 cable. Be sure to adjust the selector switch on the Sensor hub port to the left and plug the breakout cable2-pin connector with the same color into an available sensor port on your eGauge. See: Sensor Hub Installation for more details.

Step 2: Connect the 4-20 mA output that you want to measure to the SIG and Ground (⏚) ports on the EC420 Sensor.  The +5V port will remain unused.

Step 3: Configure the sensor in the eGauge configuration by scanning the port with the CTid function. Please see this article for more information regarding configuration of CTid sensors.

Step 4:  After scanning  the sensor, set up the registers to record the 4-20 mA signal and calculate the value of the raw signal. For information regarding basic eGauge configuration please see: Getting Started with eGauge Configuration

Expand the section below for register examples:

Register Configuration

The EC420 will report and record the milliamp value as a decimal number. The milliamp value can be linearly mapped to the actual sensor value and unit by using a formula register with function map420 (x: number, min: number, max: number) where xis the register value, min is the minimum sensor value (reported when the input is 4mA or lower) and max is the maximum value (reported when the input is 20mA or greater).

The unit of the sensor's measurement is determined by the formula register type selected.

Generally, the instantaneous register value of the raw 4-20mA sensor reading will be used for x. To get an instantaneous register value, use the format of $"Register Name" like in the examples shown below.

Examples

If a 4-20mA sensor is connected to the meter's S3 input, measuring the output of a CO2 meter that reads between 0 and 10,000 ppm, the formula register will be:

 map420($"4-20mA sensor raw value", 0, 10000)

 

Similarly, a temperature sensor that can read between -50 °C and 200 °C would have a formula register of:

map420($"4-20mA temp sensor raw value", -50, 200)

 

This assumes the minimum and maximum values of the sensor range start at 4mA and end at 20mA.

 

 

Troubleshooting and Tips

• Issue: My sensor is not scanning
  • Solution: Be sure the Sensor Hub is powered by 5 Vdc and that the selection switch on the port being used is in the Left position.
  • Solution: Make sure the correct color plug from the Sensor Hub breakout cable is being used. Plugs match the same color port on the sensor hub.

Additional Resources

Typical Setup Diagram