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Warning
AWS IoT Core supports messages with a maximum message length of 128KB. If messages are received that exceed this limit AWS IoT Core will disconnect the client.  Review our HowTo on ways to identify and resolve if this occurs

The document comprises these sections:

Table of Contents
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Provisioning the 'Thing'

Before configuring MQTT Engine or MQTT Transmission, you must register a 'thing' connection in AWS IoT Core. Begin by browsing to AWS IoT Core in your AWS account. Make sure you are in the same AWS region that you intend to connect the MQTT Module to. Begin by expanding 'Secure' and click 'Policies' as shown below.

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• UUID.certificate.pem.crt
• UUID.private.pem.key
• AmazonRootCA1.pem

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engine engine

Configuring MQTT Engine

Using the Ignition Gateway Web UI, browse to the Ignition 'Config > MQTT Engine Settings > Servers' page. Now click the 'Certificates' tab as shown below:Image RemovedImage Added

Now click the 'Create new Certificate' link. Then upload one of the three files previously downloaded when creating the IoT Core 'Thing'. Once completed, your Certificates page should look similar to the following with all three files.Image RemovedImage Added

Now, click the 'Servers' tab as shown below.

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If you are only going to be connecting to AWS IoT Core, edit the existing 'Chariot SCADA' setting. Otherwise, create a new MQTT Server Setting. This should bring up the following page.Image RemovedImage Added

Set the following.

• Name
  • AWS IoT Core
• URL
  • The URL that was captured from the AWS IoT Core setting page. It should be of the form: ssl://ENDPOINT_URL:8883
  • Example: ssl://a33fdj134jkj10-ats.iot.us-east-1.amazonaws.com:8883
• Server Set
  • Default
• Username
  • Blank
• Password
  • Blank
  • Note if a password was previously set, make sure to click the 'Change Password' checkbox and ensure the password fields are empty
• CA Certificate File
  • The 'Root CA' that was downloaded from AWS IoT Core
• Client Certificate File
  • The 'Client Cert' that was downloaded from AWS IoT Core
• Client Private Key File
  • The 'Client Private Key' that was downloaded from AWS IoT Core.

Leave all other fields blank and submit the configuration. If everything was set up properly, the 'Status' should show 'Connected' when complete.Image Added

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CustomProperties CustomProperties

For MQTT Engine, you must also set the 'reordering timeout' due to timing issues related to IoT Core message delivery. To do this, set the Custom Properties on the MQTT Engine General tab to: { "reorderingTimeout" : 3000 } as shown below and save the changes.

This will allow MQTT Engine to buffer messages and reorder them should they be delivered out of order within a 3 second window. Generally 3 seconds seems to be plenty of time for the reordering with AWS IoT Core.

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transmission transmission

Configuring MQTT Transmission

Using the Ignition Gateway Web UI, browse to the Ignition 'Config > MQTT Transmission Settings > Servers' page. Now click the 'Certificates' tab as shown below:

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Configure an Transmitter as shown below and use Ignition Designer to created an appropriate tag tree in the default provider.

Tip
Review the MQTT Transmission Transmitters and Tag Trees document for more information on how Transmitter configs and Ignition tag trees interact

The server connection will now show the connected client as '1 of 1'

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To confirm messages are published from Transmission, navigate to the Ignition logs and Refresh Transmission. This will cause the client to disconnect and , reconnect and publish its BIRTH messages.

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On a Transmission Refresh you will see all DEATH messages published on the disconnect along with the new BIRTH messages on the reconnect.

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