This Lucid Protocol (Lucid), as set out here, adds functionality for the management of data gathering and control devices. It provides a rich set of functions, previously implemented in telemetry and remote SCADA systems using manufacturer-specific protocols.
By using a rich common standard, Lucid Protocol users can purchase and operate data sources (Field Devices) and server software (Supervisory Applications) from multiple vendors and be assured that they are compatible. This encourages competition between vendors and reduces the costs of procurement, training, operations, and maintenance.
The protocol can be used in any industry for the management of remote data gathering and control devices and for the sharing of data, events (alarms), state and configuration between server applications.
Needs to work in all common situations from application to application transferring thousands of packets per minute, for large scale field devices controlling plant and infrastructure, down to tiny devices using unreliable slow connections.
Connects devices to single or multiple applications and a wide variety of communications scenarios for any industry.
Maintains common outstation and data logging functionality. It also has the smallest cost to implement and allows existing WITS systems to share operating philosophy.
Simple to implement; built on standard protocols, techniques & features included.
Lucid is used to provide communications between a remotely deployed Field Device (FD) and one or more central Supervisory Applications (SA), and between Supervisory Applications.
The communications between FD to SA go through an intermediate Broker. So, whenever the text describes communications from an FD to an SA, or an SA to an FD, the Broker should be inferred.
Lucid supports the transmission of information from the FD to the SA. That information is generally related to Points on the FD that provide values users are interested in collecting or monitoring.
The FDs may be constrained devices of a similar nature to those deployed in Internet of Things (IoT) and Industrial Internet of Things (IIoT), or as smaller devices within Operational Technology (OT), but Lucid is not limited to these styles of devices. Indeed, Lucid may be used between SAs.
The types of functions supported by Lucid are those which from normal IoT and OT operations. The functions originally rose out of requirements within the UK Water Industry and are now considered as common functions across the whole of industrial IoT.
Point information
Definition of device capabilities
Point change reporting
Provision of security
Time-summarised Points
Logging of Point data for later retrieval
Calculated Points
Vendor customisable extensions for SA UI layout
Synchronisation of time
Monitoring & controlling device configuration
Control of Point values
Download & upgrade of device firmware
Lucid uses MQTT as a transport mechanism. Messages are exchanged over several predefined Topics in MQTT.
Lucid users publish and subscribe to these Topics to exchange messages of defined formats.
Lucid formalises the definition of the FD and SA and how they are expected to operate to allow specification of the message content. Lucid provides a definition of the JSON to be used as the content of the MQTT messages. This is provided through examples and the use of a JSON schema.
There is a many-to-many relationship between Supervisory Applications (SAs) and Field Devices (FDs). That is, an FD may report and be controlled by multiple SAs via the Broker. Also, an SA may monitor and control many FDs. The exchange of a Configuration Version (cVer) between FDs and SAs provides the mechanism to manage change.
Lucid may be used between SAs, without an FD. In this operating mode, one SA assumes the role of a population of FDs and generates Lucid Protocol content as if it were the Lucid FDs. This can be useful for sharing FD configuration, data, and control messages between Lucid SAs.
Example: This may be used where a Lucid SA also operates non-Lucid native FDs and needs to share the configuration, data, and control messages with a separate Lucid SA. This allows a pure Lucid SA to fully operate with non-Lucid FDs using an intermediary Lucid-to-Native SA.
Lucid is a free, open source protocol that bridges a gap between Operational Technology (OT) and IoT technology.
