MTConnect Concepts

FairCom Edge MTConnect connector service concepts

The FairCom Edge MTConnect service can connect to and interact with MTConnect agents. This service is included in the FairCom jsonAction API.

MTConnect organizes device data as a hierarchy. A device may have one or more components and each component may deliver sample, event, and condition data. A component may also have child components.

The FairCom MTConnect connector sends an MTConnect request to retrieve data from a device and it returns an MTConnectStreams XML document.

The MTConnectStreams contains one Header and one Streams element. If there is no available data, the Streams element may or may not be empty. It contains zero or more DeviceStream elements.

Each DeviceStream element contains data from a specific device, which is uniquely identified by its uuid attribute. Each DeviceStream element contains zero or more ComponentStream elements, which may contain data from components on a device. If a device has no data, the ComponentStream element may or may not be empty.

Each ComponentStream element contains zero or one of the Samples, Events, and Condition elements, which contain data item elements.

Each DataItem element is defined in the MTConnect device XML file and the device uses this information to generate the data item in the DeviceStream.

DataItem Examples

The following XML definition of a DataItem is from an MTConnect device XML file. Less useful attributes are omitted for better readability.

<DataItem category="EVENT" id="Device1_Avail1" type="AVAILABILITY"/>

The device uses the DataItem definition in the device XML file to generate the DataItem in the DeviceStream as follows:

<Events>
  <Availability dataItemId="Device1_Avail1" timestamp="2010-04-06T06:19:35.153141">AVAILABLE</Availability>
</Events>

Notice the following about the two XML elements:

The DataItem's category of "EVENT" causes the DeviceStream to put the DataItem inside an <Events> element.
The DataItem IDs match.
The "AVAILABILITY" type in the DataItem definition causes the device to output an <Availability> element with a value of AVAILABLE or UNAVAILABLE.

The FairCom MTConnect Connector can ignore everything in the MTConnectStreams XML except for the DataItem elements inside <Events>, <Samples>, and <Condition> elements. The names of the DataItem elements vary and are, thus, unusable. The FairCom Connector must only read the dataItemId attribute and match it to items in its "propertyMapList". It then extracts the value of the DataItem element and converts it into the data type specified by the "dataType" property in the "propertyMapList".

Example MTConnect `"propertyMapList"`

The following "propertyMapList" configures the FairCom MTConnect Connector to retrieve the value of the DataItem identified as "Device1_Act1_1" from the device identified as "Device1". The connector then creates a JSON document that contains a property named "device1Action1PositionInMillimeters" and assigns the value to it.

{
  "propertyMapList": [
    {
      "propertyPath": "device1Action1PositionInMillimeters",
      "deviceUuid": "Device1",
      "dataItemId": "Device1_Act1_1",
      "dataType": "string",
      "defaultValue": "-1",
      "useMtconnectTimestamp": true
    }
  ]
}

If the DataItem specified in the "propertyMapList" does not exist in the MTConnectStreams XML returned by the device, the FairCom Connector uses the -1 value specified by the "defaultValue" property and assigns it to the "device1Action1PositionInMillimeters" JSON property. If the "defaultValue" property is omitted from the "propertyMapList", the FairCom Connector assigns null to the JSON property.

The "dataType" property is a string. Possible values: "string" or "boolean". "string" is the default.

The "defaultValue" property can be any json value.

The "useMtconnectTimestamp" property is a boolean. It defines if we will use the Faircom timestamp (if value is false) or use the value returned from MTConnect (if the value is true). The default is false.

MTConnect startup configuration

Enable the FairCom MTConnect connector service (plugin)

Verify that the MTConnect service is enabled in the FairCom Edge server.

Edit the <faircom>/config/services.json configuration file.
In the "mtconnect" serviceName of the "integrationServices" object, set the "enabled" property to true to enable the MTConnect connector or false to disable the MTConnect service.
Save the changes.
Restart the server for the change to take effect.

Examples

Windows

"integrationServices": [  
  {
    "serviceName": "mtconnect",
    "serviceLibrary": "mtconnectservice.dll",
    "enabled": true  
  }
]

Unix/Linux

"integrationServices": [  
  {
    "serviceName": "mtconnect",
    "serviceLibrary": "mtconnectservice.so",
    "enabled": true  
  }
]

MAC

"integrationServices": [
{
  "serviceName": "mtconnect",
  "serviceLibrary": "mtconnectservice.dylib",
  "enabled": true
}

MTConnect Data Types

MTConnect supports the following native data types

Table 1. MTConnect Data Types

Data Type	Value Range
BOOL	TRUE/FALSE
INT	-32768 to 32767
UINT	0 to 65535
DINT	-2,147,483,648 to 2,147,483,647
UDINT	0 to 4,294,967,295
LINT	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
ULINT	0 to 18,446,744,073,709,551,616
REAL	0, 1.175495E-38 (Absolute value) to 3.402823E38 (Absolute value)
LREAL	0, 2.22507385850721E-308 (Absolute value) to 1.79769313486231E308 (Absolute value)
STRING	(1 to 32 characters) Example: abcdefghijklmnopqrstuvwxyz123456
WSTRING	(1 to 16 characters) Example: abcdefghijklmnopqrstuvwxyz123456

MTConnect also allows devices to define their own data types.