Information and errors messages about MQTT are logged in CTSTATUS.FCS.
There are three internal topics that publish some monitoring information in the JSON payload:
faircomAdmin/connections: Lists the active connections in the MQTT broker. Each connection will have clientID, time when the connection was established, and the list of subscribed expressions.
faircomAdmin/subscribers: Lists the active subscriber expression in the MQTT broker. Each subscriber will have topic expression, QoS (quality of service), and the list of connections subscribed to the same topic expression.
faircomAdmin/topics: Lists the topics in the MQTT broker. Each topic will have name, creation time, message count, last message time, average messages per minute, per hour, and per day, list of subscribers, and if persistence is turned ON for the topic, the basic persistence configuration.
These messages are written to CTSTATUS.FCS if "mqtt_log_enabled" is true.
