The mqtt_subscribe node
Subscribe to an mqtt-broker and get data from one or more topics.
Example
|mqtt_subscribe()
.topics('top/grips/#')
.dt_field('UTC-Stamp')
.dt_format('float_micro')
Sequence check
since version 1.5.5
This node can perform a check on data based on meta data, that gets added to each data-item by an mqtt_publish node. This data will include a sequence number that will be checked. The check will be performed after n number of items to see, if data has been lost along the way. In case of missing data, a new mqtt message will be sent out to report this. If no meta data is present in a data_point, it will be ignored in regards of the check. For more information see configuration.
Example data_point with meta data:
{
"ts": 1748438360000,
"data": {
...
}
},
"_meta": {
"topic": "data/test/seq_check/v1",
"started": false,
"seq": 4392,
"nodeid": "mqtt_publish3",
"flowid": "test1",
"device": "3a79daae29a28b4e2f754720a2bcd31c"
}
}
Parameters
| Parameter | Description | Default |
|---|---|---|
host( string ) |
Ip address or hostname of the broker | config: mqtt.host/FAXE_MQTT_HOST |
port( integer ) |
The broker's port | config: mqtt.port/FAXE_MQTT_PORT |
user( string ) |
username | config: mqtt.user/FAXE_MQTT_USER |
pass( string ) |
password | config: mqtt.pass/FAXE_MQTT_PASS |
client_id( string ) |
mqtt client id, defaults to a combination of flow-id and node-id | undefined |
topics( string_list ) |
mqtt topic(s) to use | undefined |
topic( string ) |
mqtt topic to use | undefined |
qos( integer ) |
Quality of service, one of 0, 1 or 2 | 1 |
dt_field( string ) |
name of the timestamp field that is expected | 'ts' |
dt_format( string ) |
timestamp or datetime format that is expected (see datetime-parsing) | 'millisecond' |
include_topic ( bool ) |
whether to include the mqtt-topic in the resulting datapoints | true |
topic_as ( string ) |
if include_topic is true, this will be the fieldname for the mqtt-topic value |
'topic' |
as ( string ) |
base object for the output data-point | undefined |
| ssl( is_set ) | whether to use ssl | config: mqtt.ssl.enable/FAXE_MQTT_SSL_ENABLE |
remove_meta_field( bool ) |
whether to remove meta data added by an mqtt_publish node for the seq_check feature (see here) | config: seq_check.cleanup/FAXE_SEQ_CHECK_CLEANUP |
One of
topic,topicsmust be specified.