FB_IotMqtt5UnsubscribeProperties
The function block allows the definition of various properties that can be set when a subscription is unsubscribed. This allows the following metadata to be transmitted from the client to the message broker.
General description of the Unsubscribe Properties:
Property | Description |
|---|---|
User Properties | User Properties are key/value pairs that can transport additional metadata. These are managed via the function block FB_IotMqtt5UserProperties. The meaning of the UserProperties is not part of the MQTT5 specification and therefore application specific. |
Syntax
Definition:
FUNCTION_BLOCK FB_IotMqtt5UnsubscribeProperties EXTENDS 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 |
|---|---|---|---|
pUnsubscribeProperties | POINTER TO MqttUnsubscribeProperties | Get | Pointer to an object of type MqttUnsubscribeProperties. When calling FB_IotMqtt5Client.Unsubscribe() it is possible to pass this directly. |
Methods
Name | Description |
|---|---|
SetUnsubscribeProperties | Allows to set the Unsubscribe properties. |
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) |