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.
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.
Image courtesy of eng-tip.com
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.
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).
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
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 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
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
At <Things>, select your new Thing then click on
Security > Certificates > Policies
Under <Actions>, choose to Attach a Policy:
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.
Next go back to go your AWS IoT console and subscribe to the Topic to "Test" that data is being received.