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- reading simple value types
- reading arrays (with support for the Destination column)
- writing simple value types
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- reading of template items (UDT)
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- reading of dataset items
The communication was tested/deployed with:
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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). Reading template items items is possible by specifying sparkplug_address in the format <TemplateName1><Separator><TemplateName2><Separator> ... <Separator><ItemName> where:
Examples of template item addresses: Reading dataset items (equivalent to structured variables in D2000) is possible by specifying sparkplug_address in the format <DatasetName>[<Row>]^<ColumnName> where:
Examples of dataset item addresses: For output I/O tags, the value type must be specified. Simple types are supported (not template items/dataset The value type must be specified for output I/O tags. Simple types are supported (not template items):
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). | ||||||
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