FB_IotMqtt5UserProperties

The function block enables the definition and handling of UserProperties. UserProperties are key/value pairs that describe optional metadata and can be used, for example, with PublishProperties.

	Number of UserProperties The processing of UserProperties in the PLC real-time task cycle requires a certain amount of time, which is why it is better to keep it low. The maximum amount of possible UserProperties can be set via the parameter `cMaxMqtt5UserProps` in the parameter list of the Tc3_IotBase library.

Syntax

Definition:

FUNCTION_BLOCK FB_IotMqtt5UserProperties 
VAR_OUTPUT
    bError           : BOOL;
    hrErrorCode      : HRESULT;
END_VAR

Outputs

Name	Type	Description
bError	BOOL	Becomes TRUE as soon as an error situation occurs.
hrErrorCode	HRESULT	Returns an error code if the bError output is set. An explanation of the possible error codes can be found in the Appendix.

Properties

Name	Type	Access	Description
nUserPropertyCnt	UINT	Get	Specifies the number of UserProperties included.

Methods

Name	Description
AddUserProperty	Adds a UserProperty to the list. The property is specified by its name and value.
ClearUserProperties	Deletes all UserProperties contained in the list.
GetUserPropertyByIdx	Returns the name and value of a UserProperty specified by its position (index) in the list.
GetUserPropertyValueByName	Returns the value of a UserProperty specified by its name.
SetUserProperties	Deletes all UserProperties contained in the list and adds a set of UserProperties specified by an array of objects of type MqttUserProperty.

Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT v3.1.4026.0	IPC or CX (x86, x64, ARM)	Tc3_IotBase (>= v3.4.2.0)