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Note: for a SparkPlug MQTT server, Topic has the form 'namespace/group_id/message_type/edge_node_id/[device_id]', where message_type indicates the message type (e.g. DDATA, DBIRTH, DDEATH).
A regular expression (e.g. spBv1.0/Sparkplug Devices/.*/MyDevice/Sensor2) can be used instead of message_type to cover all message types.
If Payload Type=Sparkplug, it is possible to omit the namespace and message_type parts and write the Topic in the abbreviated form 'group_id/edge_node_id/[device_id]' (e.g. Sparkplug Devices/MyDevice/Sensor2).
Note: If the station address is in abbreviated form, commands (DCMD, NCMD) are not processed for it. If it is in the form of a regular expression ('namespace/group_id/.*/edge_node_id/[device_id]'), the station also processes commands (including the command sent by the D2000 KOM process if Send Node Control/Rebirth=YES). Therefore, we recommend specifying the station address in abbreviated form. If it is also necessary to process commands (from other other Host Applications), then create another station with an address in the form of a regular expression (e.g. spBv1.0/Sparkplug Devices/DCMD/MyDevice).Kotva komunikacna_stanica_pozn komunikacna_stanica_pozn
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The Browse button opens a browse dialog for the station address. As long as the communication is functional, a dialogue with containing the Topics received so far will be displayed. The list of received topics can be cleared with the the Refresh button.
Double-clicking on a particular line will insert the value from the Address column into the configuration of the station from which the browse dialog was opened.
Note: The Station column shows the station to which the Topic has been assigned (based on the abovementioned processing priorities). For Sparkplug addresses, the abbreviated form of the address is displayed.
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- Text mode: The original implementation of the MQTT protocol contained only input text I/O tags with the addresses IN_TOPIC, IN_DATA, and optionally a pair of I/O tags with the addresses IN_ID and ACK_ID. The first two I/O tags were used to publish the received Topic and Payload (which then needed to be parsed in the script), the second two points were used to publish the packet identifier and confirm the processing of the packet. Thus, it was possible to ensure that for data sent with QoS > QoS_0, confirmation was sent only after data processing in the script.
Output I/O tags with the addresses OUT_TOPIC and OUT_VALUE are used for writing. - JSON mode: An extension for processing Payload with JSON data (Payload Type=JSON) was implemented with the help of input I/O tags with addresses JA=json_address. The D2000 KOM process directly parses the JSON payload and sets the values of I/O tagswith JSON addresses. I/O tags with addresses IN_TOPIC, IN_DATA, IN_ID, and ACK_ID may not exist at all.
Output I/O tags with the addresses OUT_TOPIC and OUT_VALUE are used for writing. - Sparkplug mode: An extension for Payload processing with Sparkplug data (Payload Type=Sparkplug) has been implemented using input I/O tags with addresses SA=sparkplug_address. The D2000 KOM process directly parses the Sparkplug payload and sets the values of I/O tags with the Sparkplug addresses. I/O tags with addresses IN_TOPIC, IN_DATA, IN_ID, and ACK_ID may not exist at all.
Writing simple values is possible using output I/O tags with addresses ST=type;SA=sparkplug_address, where type is the Sparkplug definition of a data type (eg Int8, UInt16, DateTime, String, etc). The output I/O tags must be on the station with the Sparkplug address since the Topic is derived from it when writing.
Note: STATE type messages that have a JSON payload can be parsed using I/O tags with a JSON address (typically an I/O tag of Di type with an address of JA=online).
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| Type of I/O tag | Address | Description | ||||||
|---|---|---|---|---|---|---|---|---|
| I/O tags for reading data sent by the MQTT server through a PUBLISH message. Note: values of I/O tags are set by the D2000 KOM process in the order IN_TOPIC, IN_DATA, and IN_ID. It is not necessary for the configuration to contain all three I/O tags. | ||||||||
| TxtI |
| Topic (Topic) of received PUBLISH message. | ||||||
| TxtI |
| Data (Payload) of received PUBLISH message. | ||||||
| Ci |
| Identifier of a packet (Packet Identifier) of PUBLISH message that depends on the level of validation (QoS). For messages sent with QoS_0, the identifier is zero, for QoS_1 and QoS_2, it is a positive 16-bit number. Note: if the MQTT server sends also messages with the QoS_0 level of validation and the ACK_ID I/O tag is configured, then we recommend activating the option New value when changing time in the Filter tab, so that repeated writing of the value 0 will cause a new value that differs only in a timestamp to be generated. | ||||||
| I/O tag to confirm the received data to the MQTT server. | ||||||||
| Co |
| If an output I/O tag with ACK_ID address is defined, the D2000 KOM expects confirmation of the processing of each message by writing a copy of the value of the IN_ID tag. Only after, it sets values from the next received PUBLISH message (if it was received in the meantime) into the IN_TOPIC, IN_DATA, and IN_ID I/O tags (in this order). In the case of the QoS_0 level of confirmation, it is, therefore, necessary to repeatedly set the value of the I/O tag ACK_ID to 0. If the I/O tag ACK_ID does not exist, the values are written into the IN_TOPIC, IN_DATA, and IN_ID I/O tags immediately after the PUBLISH message is received and processed. Note: for the messages received with the QoS_0 level of validation, no confirmation is sent to the MQTT server, only the values of the received PUBLISH message will be published. | ||||||
| I/O tags for sending values to the MQTT server through a PUBLISH message. Note: in order for the D2000 KOM process to send the PUBLISH messages to the MQTT server, both I/O tags must be defined within one station. | ||||||||
| TxtO |
| The topic of the PUBLISH message being sent. | ||||||
| TxtO |
| Data (Payload) of the PUBLISH message being sent. Note: sending the message is performed out as a result of writing to the OUT_VALUE I/O tag (i.e. if the Topic does not change then it is sufficient to set the OUT_TOPIC point once - e.g. by using default value). | ||||||
| I/O tags for parsing JSON messages | ||||||||
TxtI, TxtO, Qi, |
| If Payload Type=JSON, the message is parsed as JSON data. The json_address value specifies the name of the JSON field whose value is to be assigned to the I/O tag. For other examples, see the description of the LoRaWAN protocol's Envelope type I/O tags. | ||||||
| I/O tags for parsing Sparkplug messages | ||||||||
TxtI, TxtO, Qi, |
SA=sparkplug_address Output I/O tags: | If Payload Type=Sparkplug, the message is parsed as Sparkplug data (a binary format built on Google Protocol Buffers). Sparkplug data contains metrics that have text identifiers (sparkplug_address). The value type must be specified for output I/O tags. Simple types are supported:
The PUBLISH message created during writing contains a Topic derived from the station address. The message type depends on the station address - whether it is Edge Node (NCMD) or Device/Sensor (DCMD). The Payload contains a timestamp, a value type (type), a written value (encoded according to the specified value type), and a metric name (sparkplug_address). | ||||||
Note: it is also possible to monitor the status of other Sparkplug Host Applications connected to the MQTT server. If the Identifier of Host Application is e.g. "ACME", so it is necessary to create a station with the address "spBv1.0/STATE/ACME" (or in abbreviated form "ACME") and on it an I/O tag of type Di with the address "JA=online" (since the Host Application sends a STATE message with a JSON payload).
Browse
For the I/O tags, it is possible to discover the list of objects, as long as the KOM process is running and communication with a station is established.
Clicking the Browse button opens the MQTT Item Browser window and displays a list of received metrics. The object list is created dynamically as a result of received messages.
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