Select a different adapter, please see respective documentation for more information
Adapter Setting (MQTTServerSettings)
File path to the policy file
Warning : <Make sure to fill in a relative path to the Asset folder of the project and include .xml file extension>
Is used as the an indicator in the XML policy file
The address of the MQTT broker. This can be a be in IPv4 address or a hostname like localhost
The port on which the MQTT broker is running, the default port is 1883
Should be turned on when the broker is using TLS authentication. (off by default)
Default port for MQTT over TLS is 8883, please check your broker for the correct port
Is passed to the server for authentication if the field is not empty (not used by default)
Is passed to the server for authentication when the UserName field is not empty (not used by default)
(Quality Of Server) is an agreement between the broker and client that defines the guarantee of delivering a message:
0 : At most once => There is acknowledgement between broker and client other than regular TCP , fast, unreliable (packet loss))
1 : At least once => The sender buffers the value until a ‘PUBACK’ is returned by the broker. Message can be sent multiple times (, slower, reliable)
2 : Exactly once => The sender sends the message, the broker returns a ‘PUBREC’. The sender is returning a ‘PUBREL’ and the server again returns a ‘PUBCOMP’ command to finalize the sending process. (slow, very reliable)
See below for more detail.
Not implemented for MQTT
QoS (Quality of Server) - Detailed agreements
fire & forget
Messages can get lost in unstable connections. Very suitable for wires local connection
No message is lost. Can lead to duplicate messages. but is much faster than QoS 2
If getting the message exactly once is more important than performance. Quite an overhead compared to the other 2 levels
To communicate with the MQTT adapter in Prespective you need to apply the following protocol:
The structure for the message is:
Topic to write is the address defined by the PLC address in the signal naming
Value is the value that is within the range of the specified type
Setting up the component works as like any other prelogic component. The thing you have to take into account is how the PLC Address Path Format (or implicit naming rule) is configured. The output of this Address is the topic to which the component is reading and/or writing.
WARNING : < Make sure both paths are unique >
Each defined input writes the value to the PLC address path topic.
Each defined output reads the value from the PLC address path topic.
The PLC path separator has to be '/'
< Spaces are allowed but not recommended >
A leading '/' is not recommended because it leads to an extra parent topic with id 0.
For an overview of all variables for signal naming, please go to the prelogic component page.