End of support notice: On October 7th, 2026, AWS will discontinue support for AWS IoT Greengrass Version 1. After October 7th, 2026, you will no longer be able to access the AWS IoT Greengrass V1 resources. For more information, please visit [Migrate from AWS IoT Greengrass Version 1](https://docs.aws.amazon.com/greengrass/v2/developerguide/migrate-from-v1.html). # Modbus-TCP Protocol Adapter connector The Modbus-TCP Protocol Adapter [connector](connectors.md) 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](http://docs.aws.amazon.com/iot-sitewise/latest/userguide/configure-modbus-source.html) in the IoT SiteWise user guide. **Note** This connector runs in [No container](lambda-group-config.md#no-container-mode) isolation mode, so you can deploy it to a AWS IoT Greengrass group running in a Docker container. This connector has the following versions. | Version | ARN | | --- | --- | | 3 | `arn:aws:greengrass:region::/connectors/ModbusTCPConnector/versions/3` | | 2 | `arn:aws:greengrass:region::/connectors/ModbusTCPConnector/versions/2` | | 1 | `arn:aws:greengrass:region::/connectors/ModbusTCPConnector/versions/1` | For information about version changes, see the [Changelog](#modbus-tcp-connector-changelog). ## Requirements This connector has the following requirements: ------ #### [ Version 1 - 3 ] + AWS IoT Greengrass Core software v1.10.2 or later. + Stream manager enabled on the AWS IoT Greengrass group. + Java 8 installed on the core device and added to the `PATH` environment variable. **Note** 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: `LocalStoragePath` The directory on the AWS IoT Greengrass host that the IoT SiteWise connector can write persistent data to. The default directory is `/var/sitewise`. Display name in the AWS IoT console: **Local storage path** Required: `false` Type: `string` Valid pattern: `^\s*$|\/.` `MaximumBufferSize` The maximum size in GB for IoT SiteWise disk usage. The default size is 10GB. Display name in the AWS IoT console: **Maximum disk buffer size** Required: `false` Type: `string` Valid pattern: `^\s*$|[0-9]+` `CapabilityConfiguration` The set of Modbus TCP collector configurations that the connector collects data from and connects to. Display name in the AWS 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": "127.0.0.1", "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 (AWS 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\":\"127.0.0.1\",\"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}]}\"}" } } ] }' ``` **Note** The Lambda function in this connector has a [long-lived](lambda-functions.md#lambda-lifecycle) 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" } ] } ``` ## Licenses The Modbus-TCP Protocol Adapter connector includes the following third-party software/licensing: + [Digital Petri](https://github.com/digitalpetri/modbus) Modbus This connector is released under the [Greengrass Core Software License Agreement](https://greengrass-release-license.s3.us-west-2.amazonaws.com/greengrass-license-v1.pdf). ## Changelog The following table describes the changes in each version of the connector. | Version | Changes | Date | | --- | --- | --- | | 3 (recommended) | This version contains bug fixes. | December 22, 2021 | | 2 | Added support for ASCII, UTF8, and ISO8859 encoded source strings. | May 24, 2021 | | 1 | 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](connectors.md#upgrade-connector-versions). ## See also + [Integrate with services and protocols using Greengrass connectors](connectors.md) + [Getting started with Greengrass connectors (console)](connectors-console.md) + [Getting started with Greengrass connectors (CLI)](connectors-cli.md)