# Communication between Greengrass Core and Ignition MQTT Transmission Module

**URL:** <https://forum.inductiveautomation.com/t/communication-between-greengrass-core-and-ignition-mqtt-transmission-module/35023>\
**Category:** 3rd Party Modules\
**Created:** [May 25, 2020, 8:54pm UTC](https://forum.inductiveautomation.com/t/communication-between-greengrass-core-and-ignition-mqtt-transmission-module/35023 "2020-05-25T20:54:22Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ssg](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@ssg](https://forum.inductiveautomation.com/u/ssg)\
**Post date:** [May 25, 2020, 8:54pm UTC](https://forum.inductiveautomation.com/t/communication-between-greengrass-core-and-ignition-mqtt-transmission-module/35023/1 "2020-05-25T20:54:22Z")

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Hi,

I am new to AWS and trying the Communication between Greengrass Core and Ignition MQTT Transmission Module, followed all the instructions as per the below article but still not able to establish communication link between AWS Greengrass Core and Ignition Transmission Module.

> **[Connecting disparate industrial systems to AWS using Ignition Edge | Amazon...](https://aws.amazon.com/blogs/iot/connecting-disparate-industrial-systems-to-aws-using-ignition-edge/)**
>
> Enabling operational data connectivity to AWS IoT Greengrass seamlessly extends AWS to the edge to provide tools to act locally on the OT data, while still using the cloud for management, analytics, and durable storage. With AWS IoT Greengrass and...

Below are the error messages in Ignition Gateway:

MyIgnition2: connect failed due to Unable to connect to server

**rg.eclipse.paho.client.mqttv3.MqttException: Unable to connect to server**

**at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:90)**

**at org.eclipse.paho.client.mqttv3.internal.SSLNetworkModule.start(SSLNetworkModule.java:92)**

**at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:676)**

**at java.base/java.lang.Thread.run(Unknown Source)**

**Caused by: java.net.ConnectException: Connection refused (Connection refused)**

**at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)**

**at java.base/java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)**

**at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)**

**at java.base/java.net.AbstractPlainSocketImpl.connect(Unknown Source)**

**at java.base/java.net.SocksSocketImpl.connect(Unknown Source)**

**at java.base/java.net.Socket.connect(Unknown Source)**

**at java.base/sun.security.ssl.SSLSocketImpl.connect(Unknown Source)**

**at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:81)**

**… 3 common frames omitted**

Can anyone suggest where I should look for logs in AWS Greengrass and what could be the problem?

Regards,  
SSG