Modbus-TCP Protocol Adapter connector - Amazon IoT Greengrass
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Amazon IoT Greengrass Version 1 entered the extended life phase on June 30, 2023. For more information, see the Amazon IoT Greengrass V1 maintenance policy. After this date, Amazon IoT Greengrass V1 won't release updates that provide features, enhancements, bug fixes, or security patches. Devices that run on Amazon IoT Greengrass V1 won't be disrupted and will continue to operate and to connect to the cloud. We strongly recommend that you migrate to Amazon IoT Greengrass Version 2, which adds significant new features and support for additional platforms.

Modbus-TCP Protocol Adapter connector

The Modbus-TCP Protocol Adapter connector collects data from local devices through the ModbusTCP protocol and publishes it to the selected StreamManager streams.

You can also use this connector with the IoT SiteWise connector and your IoT SiteWise gateway. Your gateway must supply the configuration for the connector. For more information, see Configure a Modbus TCP source in the IoT SiteWise user guide.


This connector runs in No container isolation mode, so you can deploy it to a Amazon IoT Greengrass group running in a Docker container.

This connector has the following versions.









For information about version changes, see the Changelog.


This connector has the following requirements:

Version 1 - 3
  • Amazon IoT Greengrass Core software v1.10.2 or later.

  • Stream manager enabled on the Amazon IoT Greengrass group.

  • Java 8 installed on the core device and added to the PATH environment variable.


This connector is only available in the following regions:

  • ap-southeast-1

  • ap-southeast-2

  • eu-central-1

  • eu-west-1

  • us-east-1

  • us-west-2

  • cn-north-1

Connector Parameters

This connector supports the following parameters:


The directory on the Amazon IoT Greengrass host that the IoT SiteWise connector can write persistent data to. The default directory is /var/sitewise.

Display name in the Amazon IoT console: Local storage path

Required: false

Type: string

Valid pattern: ^\s*$|\/.


The maximum size in GB for IoT SiteWise disk usage. The default size is 10GB.

Display name in the Amazon IoT console: Maximum disk buffer size

Required: false

Type: string

Valid pattern: ^\s*$|[0-9]+


The set of Modbus TCP collector configurations that the connector collects data from and connects to.

Display name in the Amazon IoT console: CapabilityConfiguration

Required: false

Type: A well-formed JSON string that defines the set of supported feedback configurations.

The following is an example of a CapabilityConfiguration:

{ "sources": [ { "type": "ModBusTCPSource", "name": "SourceName1", "measurementDataStreamPrefix": "SourceName1_Prefix", "destination": { "type": "StreamManager", "streamName": "SiteWise_Stream_1", "streamBufferSize": 8 }, "endpoint": { "ipAddress": "", "port": 8081, "unitId": 1 }, "propertyGroups": [ { "name": "GroupName", "tagPathDefinitions": [ { "type": "ModBusTCPAddress", "tag": "TT-001", "address": "30001", "size": 2, "srcDataType": "float", "transformation": "byteWordSwap", "dstDataType": "double" } ], "scanMode": { "type": "POLL", "rate": 100 } } ] } ] }

Create Connector Example (Amazon CLI)

The following CLI command creates a ConnectorDefinition with an initial version that contains the Modbus-TCP Protocol Adapter connector.

aws greengrass create-connector-definition --name MyGreengrassConnectors --initial-version ' { "Connectors": [ { "Id": "MyModbusTCPConnector", "ConnectorArn": "arn:aws:greengrass:region::/connectors/ModbusTCP/versions/3", "Parameters": { "capability_configuration": "{\"version\":1,\"namespace\":\"iotsitewise:modbuscollector:1\",\"configuration\":\"{\"sources\":[{\"type\":\"ModBusTCPSource\",\"name\":\"SourceName1\",\"measurementDataStreamPrefix\":\"\",\"endpoint\":{\"ipAddress\":\"\",\"port\":8081,\"unitId\":1},\"propertyGroups\":[{\"name\":\"PropertyGroupName\",\"tagPathDefinitions\":[{\"type\":\"ModBusTCPAddress\",\"tag\":\"TT-001\",\"address\":\"30001\",\"size\":2,\"srcDataType\":\"hexdump\",\"transformation\":\"noSwap\",\"dstDataType\":\"string\"}],\"scanMode\":{\"rate\":200,\"type\":\"POLL\"}}],\"destination\":{\"type\":\"StreamManager\",\"streamName\":\"SiteWise_Stream\",\"streamBufferSize\":10},\"minimumInterRequestDuration\":200}]}\"}" } } ] }'

The Lambda function in this connector has a long-lived lifecycle.

Input data

This connector doesn't accept MQTT messages as input data.

Output data

This connector publishes data to StreamManager. You must configure the destination message stream. The output messages are of the following structure:

{ "alias": "string", "messages": [ { "name": "string", "value": boolean|double|integer|string, "timestamp": number, "quality": "string" } ] }


The Modbus-TCP Protocol Adapter connector includes the following third-party software/licensing:

This connector is released under the Greengrass Core Software License Agreement.


The following table describes the changes in each version of the connector.




3 (recommended)

This version contains bug fixes.

December 22, 2021


Added support for ASCII, UTF8, and ISO8859 encoded source strings.

May 24, 2021


Initial release.

December 15, 2020

A Greengrass group can contain only one version of the connector at a time. For information about upgrading a connector version, see Upgrading connector versions.

See also