Online State

Associated with: MQTT Sparkplug™ B EoN Nodes and MQTT Sparkplug B Devices

Use this Online State status attribute in conjunction with the Online State Alarm attribute to ascertain the connection status of the selected MQTT Sparkplug B EoN Node or Device.

With an MQTT Sparkplug B EoN Node, the possible values of the Online State status attribute are:

• False, no NBIRTH received—This value indicates that one of the following applies:

  • The driver has never attempted to use the EoN Node database item for communications with a broker. This applies, for example, to an EoN Node item that has been added to the Geo SCADA Expert database, but has not yet been placed In Service.
  • Geo SCADA Expert has attempted to communicate with the EoN node that the EoN Node database item represents, but the node has not sent a NBIRTH message.

  Once the driver communicates successfully with the node to which the EoN Node database item represents, the Online State status attribute updates to display one of the values shown below.

• True, NBIRTH received <date and time>—This value indicates that the node is online and capable of communicating with the broker. The driver received the Sparkplug birth certificate for the node at the time and date shown. The NBIRTH indicates that the node is online and so capable of transmitting and/or accepting data.

• False, NDEATH received <date and time>—This value indicates that the driver received the Sparkplug death certificate from the node at the time and date shown. This indicates that the node has gone offline. As such, Geo SCADA Expert is no longer able to communicate with that node.

  If the node has gone offline unexpectedly, use other status attributes, such as the EoN Node's Quality status attribute, along with the Events List and/or Alarms List, to help determine the reason for that change in status. Also check the Subscription State of the MQTT Sparkplug B Group with which the EoN Node is associated, and the Connection State of the MQTT Sparkplug B Broker.

  If an EoN node goes offline, the Online State of any devices that are associated with that node will initially remain unchanged. The Online State of those devices will continue to indicate a value of 'True' until the driver has received the Sparkplug death certificates from those devices. However, the devices will display a 'Comm Failure' Quality to indicate that the EoN node with which they are associated is not responding and therefore deemed to have gone offline.

With an MQTT Sparkplug B Device, the possible values of the Online State status attribute are:

• False, no DBIRTH received—This value indicates that one of the following applies:

  • The driver has never attempted to use the Device database item for communications with a broker. This applies, for example, to a Device item that has been added to the Geo SCADA Expert database, but has not yet been placed In Service.
  • Geo SCADA Expert has attempted to communicate with the device that the Device database item represents, but the device has not sent a DBIRTH message.

  Once the driver communicates successfully with the physical or logical device or sensor to which the Device database item relates, the Online State status attribute updates to display one of the values shown below.

• True, DBIRTH received <date and time>—This value indicates that the device is online and capable of communicating with the broker. The driver received the Sparkplug birth certificate for the device at the time and date shown. The DBIRTH indicates that the device is online and so capable of transmitting and/or accepting data.

• False, DDEATH received <date and time>—This value indicates that the driver received the Sparkplug death certificate from the device at the time and date shown. This indicates that the device has gone offline. As such, Geo SCADA Expert is no longer able to communicate with that device.

  If the device has gone offline unexpectedly, use other status attributes, such as the Device's Quality status attribute, along with the Events List and/or Alarms List, to help determine the reason for that change in status. Also check the Online State status attribute of the MQTT Sparkplug B EoN Node with which the Device is associated.

  If the EoN node goes offline, the Online State of any devices that are associated with that node will initially remain unchanged. The Online State of those devices will continue to indicate a value of 'True' until the driver has received the Sparkplug death certificates from those devices. However, the devices will display a 'Comm Failure' Quality to indicate that the EoN node with which they are associated is not responding and therefore deemed to have gone offline.

Also see Online State Alarm.