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This driver acts as an MQTT broker for Hsyco, it fully supports MQTT version 3.1.1. This broker is also ready to communicate with MQTT version 5.0 although full support to this version will be introduced later.

HSYCO Configuration

Add the MQTTBROKER I/O Server in the I/O Servers section of the Settings and set its parameters:


  • User: optional default username for clients
  • Password: optional default password for clients

Authentication file

Under the hsyco root directory must be present a file named "mqttbroker.ini" which can contain a series of line, each line represents the credentials of a client and can have the following format:




Clientid must be present in each line while username and password are optional; if username and password are not present there will be two cases:

  • if default username and password are specified in "hsyco.ini" they will be used by the authentication mechanism
  • if default username and password are not specified in "hsyco.ini" the authentication mechanism is disabled

Client identifiers are considered as case insensitive when they are registered to the MQTTBROKER, so there can't be two identifiers with the same sequence of characters in upper/lower case, e.g. "MQTT_Client" and "mqtt_client" are considered the same so they cannot be registered both on the MQTTBROKER.


ID Default Values Description
startupevents true true generate IO events also during the driver’s start-up phase
false start generating events only after HSYCO is aligned with the current status of the system
acceptunknown false true accept connection from clients whose id isn't specified in mqttbrokerauth.ini
false doesn't accept connection from clients whose id isn't specified in mqttbrokerauth.ini
localport 1883 <portNumber> local port for incoming client connection
maxthreads 64 n > 0 max number of clients connected simultaneously

MQTTBroker Utility

Use the MQTTBroker Utility to automatically discover new clients or configure existing ones.


ID Value R/W Description
connection online R the broker is ready to accept connections from clients
offline R initialization of the driver failed or loop cycle failed
client.<clientId>.connected 1 R clientId is connected to the broker
0 R clientId isn't connected to the broker
client.<clientId>.publish.<topicName> <message> R clientId published a message on topicName
client.<clientId>.willpublish.<topicName> <message> R MQTTBROKER published the will message of clientId, on topicName, because of connection problems or protocol violations
client.<clientId>.lastseen <ts> R timestamp of the last message or ping sent by clientId to the broker
client.<clientId>.subscribe.<topicName> subscribed, <n> R clientId subscribed to topicName with QoS = <n>
unsubscribed R clientId unsubscribed from topicName
publish.<topicName> <message> R/W MQTTBROKER published a message on topicName

<clientId> field in datapoints will be reported with whitespaces replaced with '_'

<topicName> field is case insensitive and will be reported in lower case, furthermore the MQTT broker will replace every whitespace present in the topic name with '_'. E.g. if a client publishes a message or subscribes to "Topic Test", the MQTT broker will convert this value in "topic_test" and this change will be reflected in <topicName> field present in datapoints


All the informations about client sessions are not persistent so they will be lost in case of driver restart. The MQTT broker can maintain up to 1024 client sessions and up to 1024 retain messages in memory, every new item will replace the oldest one.

The MQTT broker can manage up to 10000 in/out MQTT messages every seconds.

Release Notes


  • improved UTF-8 characters support


  • initial release