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Connecting a RS Pro kWh energy meter to AWS IoT platform with the FATBOX G3 Gateway

Cloud monitoring energy usage via Modbus RTU

  • In this tutorial, we will set up a RS Pro 45A kWh Energy Meter as a Modbus RTU slave and interface to our FATBOX G3 gateway Modbus master.

  • The gateway is able to support up to 32 Modbus devices, including meters and remote I/O terminal. The standard industrial Modbus/RTU protocol runs on Serial RS-485 interface, providing a robust & reliable interface.

  • We will also look at connecting the G3 IOT Gateway to AWS IoT. Supported clients are AWS IoT, Azure IoT Hub and Ubidots.

  • Users have the option of backhaul via either wired Ethernet, WIFI or cellular (4G/3G) for remote sites/redundancy.


Hardware Wiring



​Above shows the Serial RS-485 connection usually implemented using shielded twisted pair cable.

Note maximum cable length depends on baudrate and cable quality, e.g. using 24AWG shielded twisted pair, about 100Kbit/sec at 1000m.

Screen Shot 2020-03-10 at 2.56.39 pm.png

Image courtesy of

RS Pro Meter Configuration

Use the front display/button to set the serial parameters as below.


All slave devices connected on the RS-485 network must each have a unique address ranging from 1 to 247. Also, the baudrate and parity for all slave devices and master must be the same.


Connect Meter to Gateway

Our gateway uses a device configuration file called iotasset to map the required Modbus registers to be read during each polling cycle. This flexibility allows wide  compatibility with most Modbus RTU devices from different manufacturers.

To setup this device configuration file, we will be referencing the Modbus register table from the product user manual (see sample below):


And here is a sample of the iotasset. In the top example, we are configuring to read Current (A) register from meter Modbus address 1, register 30007 and name data field name, as "M1_Current". 

The gateway is able to apply a customer multiplier (x0.1 in this case) and offset (0 in this case) to match the requirements of their cloud service.





















We will now configure the gateway's serial port to operate as required for the attached Modbus devices. Go to the Port Settings tab and enter the following settings.

Screen Shot 2020-03-05 at 3.41.40 pm.png

Then, go to the IoT Hardware menu to set the Hardware interface to "Modbus master" and register the polling configuration as required by the user (Note that all other interfaces like CAN bus and Zigbee can also run concurrently).

Schneider hardware settings

After these settings are updated, REBOOT the gateway. The user can then check the Modbus sensor data collected (JSON Data) or delete for testing.

Once you have configured your iotasset file the new device configurations can be updated to your FATBOX gateway securely over the air. The gateway HTTPS connected webconsole must be accessible, either via local network (LAN or WLAN) and over cellular network with assigned public IP address (If you do not have an Internet connection, you can follow the alternative steps here). 

Log into your web console and go to the <IoT Hardware> tab, click on 'UPDATE FIRMWARE' in the Firmware Update section

ota iotasset upload.png

In the new window, click on 'CHOOSE FILE' and select from your local folder the updated iotasset.txt file then click on 'UPLOAD FIRMWARE FILE'After the upload is successful you will need to close the page and log in again for security purpose.

connect meter to g3

Connect to a Cloud Service

Now that the connectivity between the RS Pro Meter and the G3 gateway has been set, we will then look at getting the data onto a suitably designed dashboard for monitoring on a custom cloud platform like Azure IoT, AWS IoT, Google Compute or an end solution like Ubidots.


For this project, we are going to showcase using AWS IoT cloud platform.  

1. Create a new AWS IoT Thing

First log into your AWS IoT Management Console and create a Thing:

AWS IoT > Manage > Thing > Create

Next go to:

Secure > Certificates

Then download the 'Certificate' & 'Private Key File'.

Ensure the Certificate is "Active", otherwise activate it under ACTIONS in 

Things > Your Certificate > Security

AWS Certificate Download.png
2. Update your G3 IoT Gateway
Create a new local folder and name it "AWS". 

Save the downloaded certificate files into this folder and rename them as the following:



Next zip the folder (ensure that you zip the entire folder and not just the files inside).

Then log into your FATBOX G3 web console and go to the <Management> tab.

Patch the zipped folder to the gateway using the UPDATE FIRMWARE button.

3. Create a Security Policy for your Thing

In your AWS IoT Management Console go to:

Secure > Policies > Create

Create AWS Policy.png
At <Things>, select your new Thing then click on

Security > Certificates > Policies

Under <Actions>, choose to Attach a Policy:

Attach AWS Policy.png
4. Configure your G3 IoT Gateway to send data to your AWS Account

Now, you are ready to configure your gateway to send AWS IoT endpoint to feed data to your AWS applications. In the FATBOX G3 web configuration menu, go to the <IoT Client> tab and configure your AWS client settings according as per your AWS end point and Thing settings. Then REBOOT your gateway.

AWS Configure G3.png
Next go back to go your AWS IoT console and subscribe to the Topic to "Test" that data is being received.

AWS receive test.png
Congratulations! You have succesfully sent your Modbus or CAN bus data to your AWS IoT endpoint and ready to, for example, push the data to a S3 bucket using a Rule in 'Act > Rules'.
The FATBOX G3 AWS IoT client side is built using AWS IoT Device SDK for Python and users are free to install, modify our device client codes for enhanced edge capabilities or other required functionalities.
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