MQTT

TagSource

Field	Note
host, topic	required
port	default 1883
username / password	optional
tls / caPem	rustls
lastWillTopic + lastWillPayload	both together
qos	0 (default) | 1

Connection: LWT/QoS at the endpoint. Point: { "protocol":"mqtt", "topic":"…" }.

Operate: PUBLISH to a concrete topic (retain). Writes to wildcard topics are rejected. Default QoS via VION_MQTT_QOS.

MQTT 3.1.1. Sparkplug is a separate protocol.