Actions that are Specific to MQTT Sparkplug™ B Points

MQTT Sparkplug B Points support actions that are common to points on many drivers, however be aware of the following with regard to this common pick action:

• Control.
  WARNING

  Potential unsuccessful Attempts to Execute a control

  Ensure that you check that any Control actions have completed as expected. To do this, you might be able to check that the output point's Current Value status attribute, or another metric's value, changes as expected. The value change should occur once the relevant EoN node or Sparkplug B device next publishes the point's or other metric's new value.

  WARNING indicates a hazardous situation which, if not avoided, could result in death or serious injury.

  If an EoN node or Sparkplug B device goes offline, the Control pick action will remain available on output points on that offline item until Geo SCADA Expert gets notified of that item's offline status. A Sparkplug B feature exists that is designed to advise the MQTT broker of an unsolicited communications failure (using a DEATH certificate), however an EoN node or Sparkplug B device could 'cleanly' disconnect of its own volition of which the MQTT broker might be unaware. With such a scenario, users with the relevant access and permissions will still be able to use the Control pick action, but the control message will not reach its intended target.

  Be aware that a control success message will still appear in the Events List, however this indicates that the control message has reached the MQTT broker; it does not indicate that the broker has forwarded the control message, nor that the message has successfully reached the EoN node or Sparkplug B device. Likewise, the output point's Control Alarm status attribute will only indicate if there has been an issue with the attempt to send the control message to the MQTT broker.

  Ensure that you check that the relevant EoN node or Sparkplug B device has successfully received and actioned each Control request. To do this, after issuing a control, you might be able to check that the point's Current Value status attribute, or another metric's value, then changes as expected in response to that control request. With a successful control, the EoN node or Sparkplug B device on which the point or other metric is located should publish that point's or other metric's new value. Once Geo SCADA Expert has received and processed that data, it will update that point's or other metric's Current Value in the database. You can view the value on the output or other point's Status display, or on the Points List that you can display from the MQTT Sparkplug B EoN Node or MQTT Sparkplug B Device with which the point or other metric is associated (see Actions that are Specific to MQTT Sparkplug™ B EoN Nodes, and see Actions that are Specific to MQTT Sparkplug™ B Device Items). As always, use the Current Value status attribute in conjunction with other associated status attributes to assess the reliability of each point's data (see Status Attributes Associated with Points).