describeOutputs

JSON hub "describeOutputs" action returns all available information about each specified FairCom Edge output

The "describeOutputs" action returns all available information about each specified output. Outputs deliver tags from the server to external systems.

Note A tag is a piece of named data with an associated value. For example, the tag temperature 70 includes both the named data temperature and the value 70. In JSON, a tag is a JSON property, such as "temperature": 70. In a SQL table, a tag is a data field, such as a field named temperature with a value of 70.

 

Request examples

Minimal

{
  "apiVersion": "1.0",
  "requestId":  "optionalUniquerequestIdFromTheClient",
  "action":     "describeOutputs",
  "params":     {
    "outputNames": [ "AcmefactoryLine1Station1AcidbathTelemetryOutput" ]
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}
 
 

 

Response examples

Minimal

{
    "result": {
        "data": []
    },
    "requestId": "00000006",
    "errorCode": 0,
    "errorMessage": ""
}
 
 

Maximal

{
  "result": {
    "data": [
      {
        "id": 19,
        "outputName": "modbusTCPout",
        "serviceName": "modbus",
        "databaseName": "faircom",
        "ownerName": "admin",
        "tableName": "modbustabletcp",
        
        "status": "userError",
        "stopCode": 16384,
        "stopReason": "Putting device in an uncertain error state while verifying data delivery.",


        "purpose": "Track Celsius Temperatures from devices",
        "description": "My output connector's description",
        "labels": ["temperature", "celsius"],
        "metadata": { "myProperty": "myValue" },
        
        "createdTimestamp": "2025-08-28T10:47:13.041",
        "updatedTimestamp": "2025-08-28T10:47:13.041",
        "inactiveTimestamp": null,
        "lastDeliveredTimestamp": null,
        "lastConnectedTimestamp": null,
        "lastDisconnectedTimestamp": null,   
    
        "settings": {
          "modbusProtocol": "TCP",
          "modbusServer": "127.0.0.1",
          "modbusServerPort": 502,
          "propertyMapList": [
            {
              "propertyPath": "temperature",
              "modbusDataAccess": "holdingregister",
              "modbusDataAddress": 1199,
              "modbusUnitId": 5,
              "modbusDataLen": 1
            }
          ]
        },
        
        "fields": [],
        "retentionPolicy": "autoPurge",
        "retentionPeriod": 4,
        "retentionUnit": "week",
        "disableTransformSteps": false,
        "logTransformOverwrites": false
      }
    ]
  },
  "authToken": "replaceWithAuthTokenFromCreateSession",
  "errorCode": 0,
  "errorMessage": ""
}
 
 

 

Properties

Request properties ("params")

Property Description Default Type  Limits (inclusive)

outputNames

The "outputNames" property specifies the names of outputs to be used to filter the response. The response will include details about all outputs with an "outputName" that matches one of the strings in the array.

 Optional with default of []

array

 1 or more strings

 

Response properties ("result")

Property Description Type Limits (inclusive)

data

The "data" property contains a response message. Its contents are defined by the action. It is an empty array when no results are available. The following is an example of the data property from a code package action.

  "result": {
    "data": [
      {
        "codeId": 6,
        "databaseName": "faircom",
        "ownerName": "admin",
        "codeName": "convertAndCategorizeTemperature",
        "codeVersion": 1,
        "clonedCodeId": 1,
        "codeStatus": "active",
        "codeLanguage": "javascript",
        "serviceName": "javascript",
        "codeType": "module",
        "description": "optional new description",
        "metadata": {},
        "createdBy": "ADMIN",
        "createdOn": "2025-08-25T21:48:38.109",
        "updatedBy": "ADMIN",
        "updatedOn": "2025-08-25T21:48:38.109",
        "comment": "Cloned from convertTemperature",
        "codeFormat": "utf8"
      },
    ]
 array of objects The action determines its contents.

data

.createdTimestamp

 The "createdTimestamp" property is the date and time when the connector was originally created in ISO 8601 format, such as "2025-08-28T10:47:13.041". It is never null. timestamp An ISO 8601 timestamp

data

.databaseName

The "databaseName" property specifies the database that contains the tables. 

Note In the API Explorer, "defaultDatabaseName" is set to "ctreeSQL" in the "createSession" action that happens at login.

  • If the "databaseName" property is omitted or set to null, the server will use the default database name specified at login.
  • If no default database is specified during "createSession", "databaseName" will be set to the "defaultDatabaseName" value that is specified in the services.json file.
  • This property's value is case insensitive. 
 string 1 to 64 bytes

data

.description

 The "description" property assigns a description to a connector. string 1 to 512 bytes

data

.disableTransformSteps

The "disableTransformSteps" property determines if the transform steps are active without removing them from the integration table. When true, it prevents the server from running an integration table's transform steps on newly inserted records. When false, the transform steps run normally. It is useful to quickly stop a broken transform process.

 Boolelan

true

false

data

.enabled


The "enabled" property is true when a connector is allowed to connect to a device. It is false when a connector will not attempt to connect to the device.

 

 Boolean true
false

data

.fields

The "fields" property is an array of objects. Each object in the array defines a field by specifying its properties.

 

"fields": [
  {
    "autoValue": "none",
    "name": "name",
    "type": "varchar",
    "length": 50,
    "scale": null,
    "defaultValue": null,
    "nullable": false,
    "primaryKey": 0, 
    "autoValue": "none"
  }
]
 array

"autoTimestamp"

"autoValue"

"primaryKey"
"name"
"type"
"length"
"scale"
"defaultValue"
"nullable"

"primaryKey"

"autoValue"

data

.id

The "id" property is the unique identifier of an object such as a label or thing. In JSON, you may use an integer number or a string containing an integer number. The server automatically generates the "id" when you create a label and stores it in the label table as an integer. You cannot alter the "id" value. If your application needs to specify a specific numeric identifier for a label, use the "enum" property.

 integer 0 to 2147483647

data

.inactiveTimestamp

 The "inactiveTimestamp" property is the date and time when the connector was last made inactive. It is null when the connector is active. It is returned in ISO 8601 format, such as "2025-08-28T10:47:13.041". timestamp ISO 8601 timestamp

data

.labels

 The "labels" property assigns zero or more labels to a connector. You can use it to do lookups and filtering. You can display a list of existing labels, add new ones, rename them, and deprecate them.
When you use the "alterInput" or "alterOutput" actions, omit the "labels" property to leave existing labels unchanged, or specify a complete set of new labels. These actions do not allow you to change one label at a time.
You can use the "labelsFilter" property to lookup and filter connectors. 
The input and output connector actions implement the "labels" property using the Label API. 
The API stores and manages labels in the label group, "faircom/edge/labels", which allows labels to be used through FairCom Edge's APIs.
An API client can retrieve a list of all lifecycle labels by using the "listLabels" action with "partialGroupFilter": "faircom/edge/labels".
An API client should use the connector API's "labels" property to manage the labels assigned to a connector. It should not use the Label API to rename, link, or unlink connectors.		 string 1 to 64 bytes

data

.lastConnectedTimestamp

 The "lastConnectedTimestamp" property is optionally returned from the "describeInputs", "alterInput", "describeOutputs", "alterOutput" actions. 
It returns the ISO 8601 date and time of the last time the connector was connected to its device. If it has never been connected, the value is null. The following string is an example of an ISO 8601 timestamp: "2025-08-28T10:47:13.041".		 ISO 8601 timestamp The last ISO 8601 date and time the input connector was connected to its device.

data

.lastDeliveredTimestamp

The "lastDeliveredTimestamp" property is a dynamically calculated property that is optionally returned in the "outputConnectors" list from the "describeTags", and "alterTag" actions.

 

It returns the ISO 8601 date and time of the last data delivered by the output connector. If no data has been delivered, the value is null. The following string is an example of an ISO 8601 timestamp: "2025-08-28T10:47:13.041".

 ISO 8601 timestamp The ISO 8601 date and time of the last data delivered by the output connector.

data

.lastDisconnectedTimestamp

 The "lastDisconnectedTimestamp" property is optionally returned from the "describeInputs", "alterInput", "describeOutputs", "alterOutput" actions. 
It returns the ISO 8601 date and time of the last time the connector disconnected from a device or software. If it has never disconnected, the value is null. The following string is an example of an ISO 8601 timestamp: "2025-08-28T10:47:13.041".		 ISO 8601 timestamp The last ISO 8601 date and time the input connector was disconnected from its device.

data

.logTransformOverwrites

The "logTransformOverwrites" property specifies whether or not the server will add a log entry to the log field when a transform step overwrites a field. When true and a record is inserted into the integration table, the server adds log entries to the log field when a transform step overwrites a field that already contains a value. When true, it protects fields, such as source_payload, from being overwritten accidentally. 

You typically set "logTransformOverwrites" to true when testing transform steps. Once they are working as expected, you can set it to false.

If multiple "recordPath" properties write to the same JSON properties in a "tableFieldsToJson" transform, the server will return an error because "recordPath" cannot overwrite. Multiple occurrences of the "recordPath" property may reference the same property as long as the property is in different fields/tables.

Additionally, non-JavaScript transform steps cannot overwrite protected fields or the source_payload field. The only exception is that a single "tableFieldsToJson" transform step may write to the source_payload field.

You may create transform steps to take the value of one JSON property and store it in multiple fields as long as no previous transform steps have already put values in these fields. Conversely, you may take the value of one field and store it in multiple JSON properties.

Tip Ensure JavaScript transform steps do not overwrite fields updated by other transform steps. 

Do not use the "tableFieldsToJson" transform method to overwrite the source_payload field; instead, use "tableFieldsToJson" to write to a different field and use the "configureTopic" action with the "outputPayloadField" property to configure the MQTT topic to deliver that field's value to subscribers. 

Ensure SQL, JSON DB, and other APIs set the value of the source_payload field and do not set field values that transform steps update.

 Boolean

true

false

data

.metadata

The "metadata" field allows a customer to add a JSON value to an object such as a label or thing. It is typically a JSON object, but may be any JSON value. Its purpose is to provide additional metadata about the label, such as translations in multiple languages, historical value changes, etc. The "alterLabel" action can only replace this value with a new JSON value.

 JSON 0 to 65,500 bytes

data

.outputName

 The "outputName" property specifies a unique name for mapping an integration table to an output plugin to an external system. string 1 to 64 bytes

data

.ownerName

 The "ownerName" property identifies the user who owns an object (see Object owner).  string 0 to 64 bytes

data

.purpose

The "purpose" property specifies the purpose of the thing. You can use it for fast partial lookups and filtering. This API uses the Label API to manage purposes.

  • An API client can use the "listLabels" action to retrieve the purpose list. 
  • An API client can use the "alterLabel" action to rename a purpose label.
  • An API client can use the "createLabel" action to create a purpose label.
  • An API client can use the "changeLabel" action to delete a purpose label, but the API client must first use the "listInputs" or "listOutputs" actions with the "purposeFilter" property to ensure the label is unused.
 string

1 to 64 bytes

Values are managed in the Label API with the group "faircom/edge/purpose".

data

.retentionPeriod

The "retentionPeriod" property specifies how many units of data to retain. It refers to the unit of time specified by the "retentionUnit" property. For more details, see "retentionPeriod".

 integer 1 to 100

data

.retentionPolicy

The "retentionPolicy" property controls how messages are persisted. 

If not specified, the default found in the services.json file is used. Initially, it is "autoPurge".

 

retentionPolicy values:
  • "autoPurge"
    • This is the default. It is automatically applied when a new topic is created. It is preferred because it allows FairCom's servers to automatically remove messages that are older than the retention time. This helps ensure message data does not consume all storage space. It also minimizes storage costs and speeds up data access. The server partitions a table into multiple files so it can efficiently delete expired files.
  • "neverPurge"
    • This stores messages on disk and never removes them. This is useful when you need the entire history of the message stream. If message velocity is high, this can consume all storage space and cause an outage. The server creates a non-partitioned table, which is slightly faster than a partitioned table because it stores all records in one file.
 string

"autoPurge"

"neverPurge"

data

.retentionUnit

The "retentionUnit" property specifies a unit of time that the server will use to purge expired messages. For example, if you want a week's worth of messages to be purged once a week, set "retentionUnit" to "week". This property is optional.

If not specified, the default found in the services.json file is used. Initially, it is "week". 

  • This property is used in concert with "retentionPeriod" to determine retention time.
  • "retentionUnit" values:
    • "minute"
    • "hour"
    • "day"
    • "week"
    • "month"
    • "year"
    • "forever"

Note 

  • For best performance, set the "retentionUnit" to a value that keeps "retentionPeriod" between 5 and 30. 
  • When you set "retentionUnit" property to "forever" the server will not purge messages. This setting is the same as setting "retentionPolicy" to "neverPurge".
  • The "retentionUnit" and "retentionPeriod" properties are used only when the "retentionPolicy" is set to "autoPurge".

string

"minute"

"hour"

"day"

"week"

"month"

"year"

data

.running

 The "running" property is true when an input connector is collecting data or an output connector is delivering data; otherwise, it is false. A disabled connector will never be running. An enabled connector may or may not be running. Boolean

true

false

data

.serviceName

The "serviceName" property contains the name of a FairCom input or output service. 

See the "params" topic of each specific service for the requirements of this property.

The following services are available as of the V5 release:
  • "MODBUS"
  • "SIEMENSUDT2JSON"
  • "OPCUA"

Note The SQL, JSON RPC, and REST services can automatically query any integration table in FairCom's servers without requiring configuration.

Note MQTT always represents both input and output services. This is because once a topic is created and assigned to an integration table, any MQTT client can publish messages to it and subscribe to those messages.

 string A service name between 1 and 64 bytes.

data

.settings

The "settings" property contains properties that are specific for each connector type. Settings for Modbus are different than settings for OPC UA, and so forth. See the API reference "params" property of each connector for details of the "settings" property for that connector.

 object

See these pages for connector specific properties:

Allen-Bradley "params"

Modbus "params"

OPC UA "settings"

Siemens S7 "params"

data

settings

.propertyMapList

 The "propertyMapList" property specifies which data the connector requests and where to put it in the generated JSON. array of objects

See these pages for connector specific properties:

Allen-Bradley "params"

Modbus "params"

OPC UA "settings"

Siemens S7 "params"

data

settings

propertyMapList

.propertyPath

 The "propertyPath" property specifies the JSON path in the JSON document where the connector puts the data it collects. It is mutually exclusive with the "tagName" and "tagId" properties. string JSON path

data

settings

propertyMapList

.tagId

 The "tagId" property associates a tag with a value being collected by a connector. It is mutually exclusive with the "tagName" and "propertyPath" properties. See tagId for more details.
 		 integer If present, it must contain the ID of an existing tag, which is an integer from 0 to 9223372036854770000.
Note FairCom recommends using this property instead of "propertyPath".

data

settings

propertyMapList

.tagName

 The "tagName" property associates a tag with a value being collected by a connector. It is mutually exclusive with the "tagId" and "propertyPath" properties. See tagName for more details. 
 		 string

If present, it must contain the name of an existing tag. 

Note FairCom recommends using this property instead of "propertyPath".

data

.status

 The "status" property assigns an active or inactive status to a thing. An inactive status is like a soft delete. See "status" for more information.   string enum

"active"

"connectorError"

"deviceError"

"userError"

"paused"

"inactive"

data

.stopCode

 The "stopCode" property is 0 when the connector is successfully connected to its device or software; otherwise, it is non-zero. integer -2147483648 to 2147483647

data

.stopReason

 The "stopReason" property is "" when the input connector is collecting data; otherwise, it is a non-empty string. string 0 to 256 bytes

data

.tableName

The "tableName" property is a string containing the name of a table.

The table name must start with an upper or lowercase letter, must not contain special characters other than underscore "_", and can include a mix of upper-lower case characters, but are treated as case-insensitive.

 string 1 to 64 bytes

data

.thingId

 The "thingId" property associates a connector with a device or software application. It is mutually exclusive with the "thingName" property. See thingId for more details.  integer If present, it must contain the ID of an existing thing, which is an integer form 0 to 9223372036854770000.

data

.thingName

 The "thingName" property associates a connector with a device or software application. It is mutually exclusive with the "thingId" property. See thingName for more details. string 1 to 64 bytes

data

.updatedTimestamp

 The "updatedTimestamp" property is the date and time when the connector was last updated. It is the same as the "createdTimestamp" property when the connector has never been updated. It is returned in ISO 8601 format, such as "2025-08-28T10:47:13.041". timestamp ISO 8601 timestamp

 

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