Connecting a J1939 Vehicle ECU Simulator to an IoT backend platform with the FATBOX G3 Gateway


Cloud monitoring vehicle data via CAN Bus J1939 and 4G/LTE/3G

J1939 Ozen.jpg
CAN BUS G3.jpg
  • In this tutorial, we will set up a OZEN Elektronik OE91C1700 J1939 CAN BUS ECU simulator to interface with to our FATBOX G3 gateway and connect to AWS IoT.

  • Our G3 gateway is based on the iMX6 CPU with built-in CAN port functionality. The CAN bus is driven by an industrial proven high speed CAN transceiver that provides a robust & reliable interface with high noise immunity.

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

  • Users have the option of backhaul via either cellular (4G/3G), WIFI or wired Ethernet, depending on version


Hardware Wiring







OZEN Elektronik OE91C1700 (J1962 female ODB)

G3 CAN BUS port (DB9 male)




CAN High



Above shows the CAN BUS signal connection usually implemented using shielded twisted pair cable.

You can use a standard off-the-shelf ‘OBD2 male to DB9 female cable’ with pin connection as below:

ODB2-DB9 Cable.png
DB9 to OBD2.png

Ozen ECU simulator Configuration

By default the J1939 ECU Simulator CAN Bus communicates using 29-bit protocol and 250 kbps baud rate. The baud rate set on the G3 gateway CAN BUS must be same.


Connect the ECU Simulator to Gateway

Our gateway uses a configuration file (\user\iotasset.txt) to map the required Parameter Group Number (PGN) to be read from the J1939 devices. This flexibility allows wide compatibility with different J1939 CAN Bus devices from different manufacturers.

To write this iotasset.txt file we will be referencing the PGN info from the product user manual (see sample below):

PGN 1.png
PGN 2.png

And here is a sample of the iotasset.txt.


In the top example, we are configuring to read ECT (Engine Coolant Temperature).

  • “FEEE” is the PGN 0xFEEE (65262 decimal).

  • SPN=0 reserved for future development.

  • Response data is located at start byte position 1 and length of 1 byte. 

  • Name data field name, as “EngineCoolantTemp".

  • The gateway is able to apply a customer multiplier (x1 in this case) and offset (-40 in this case) to match the requirements of their cloud service.



CANPGN,FEEE                               #PGN=65262






CANPGN,F004                               #PGN=61444






CANPGN,FE63                               #PGN=65132






Once you have configured your device configuration file, we can update to your FATBOX gateway securely over the air. The gateway HTTPS connected web console must be accessible, if you do not have an Internet connection, you can follow the alternative steps here). 

Log into the G3 (the default address is and enter in the user name and password. Go to the <Management> tab in the G3 web configuration menu. Enable the SSH option (see below) and click the 'UPDATE' button to save your settings. Then reboot the gateway.


Then log in again, go to the <IOT Hardware> menu to set the CAN bus mode to "J1939 mode" and register the polling configuration as required by the user. Click 'UPDATE' to save your settings. 

(Note that all other interfaces like Modbus and Zigbee can also run concurrently).

Screen Shot 2020-07-07 at 11.22.08
Screen Shot 2020-07-07 at 11.22.16

Next, click “Upload iotasset.txt” button and in the new window, use the 'CHOOSE FILE' tab to select the above prepared file from your local folder to to send over to G3After the upload is successful you will need to close the page and log in again for security purpose. The user can also confirm the status of iotasset.txt file upload by clicking on Diagnostics::Check File.

We will now also configure the gateway's CAN BUS baud rate. Go to the <Port Settings> tab and enter the following settings below. Once you are done click the 'UPDATE' button to save your settings.


After these settings are updated, REBOOT the gateway. The user can then check the CAN BUS vehicle data collected (Diagnostics::JSON Data) or delete for testing.


Connect to AWS IoT Cloud Service

Now that the connectivity between the ECU Simulator and the G3 gateway has been set, we will then look at getting the data onto a designated cloud service. We support an open customer software and 3rd party API (e.g. REST API for HTTP, HTTPS and MQTT) integration to connect to a chosen cloud data or dashboard service (or to use for on board data processing).

 Direct deployment on Azure, AWS IoT or Ubidots can also be done as these IoT clients have been integrated on the G3 Gateway. For this project, we are going to showcase using AWS IoT
(note that an AWS
account is required to continue this tutorial).

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.

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

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.

See our guides below for connecting to other supported IoT platforms includes Azure IoT and Ubidots. Here is a sample dashboard from Ubidots. 


Guides to connect other Cloud Platforms

Connecting to Microsoft Azure IoT Hub

Connect to Ubidots IOT Platform

Have a question for us?

The FATBOX G3 Modbus to Cloud Solution was recently featured in

London IOT Tech 2019
London IOT Tech 2019
press to zoom

IoT Tech Expo Global 2018 - London

press to zoom

Electric Indonesia 2017 - Indonesia

press to zoom

IoT Tech Expo Global 2017 - Berlin

press to zoom