FB_ListQueryHmi

This class (FB) is the basis for an iterative data exchange with the corresponding HMI function ListQueryPlc. To transmit information, inherit from this class and add class properties with the data per entry. Communication takes place according to the following sequence scheme:

	Class is abstract Since the class is defined as `ABSTRACT`, the class cannot be instantiated and must be implemented using inheritance.

Syntax:

FUNCTION_BLOCK ABSTRACT FB_ListQueryHmi

Properties

Name	Type	Access	Initial value	Description
Invoke	BOOL	Get, Set	FALSE	Triggering the data request via the HMI
FB_ListQueryHmi
Current	DINT	Get	0	Counter of the current entry that was transmitted. Is incremented implicitly when `Next()` is called.
Done	BOOL	Get, (Set)	FALSE	The PLC has transferred the last entry, the query process is complete.
Results	DINT	Get, (Set)	0	Counter of the total number of results that have been loaded. Must run ahead of the `Current` counter.
Select	DINT	Get, Set	0	Selection of a value read in the previous pass. The previous `Current` counter can be requested here for identification purposes, for example. A 0 is to be treated as no selection.
Valid	BOOL	Get, (Set)	FALSE	The current data entry is fully loaded and ready for further processing by the HMI.

Methods

Type	Description
Next()	Gives the signal to process another data entry. The method resets the `Valid` flag and increments the `Current` counter.
FB_ListQueryHmi
Reset()	Resets all values (except for `Invoke`) to the initial value.

Interfaces

Type	Description
I_ListQueryHmi	Standard interface on FB_ListQueryHmi.

Prerequisites

Development environment	Target platform	PLC libraries to include
TwinCAT >= v3.1.4024.54 (recommended) TwinCAT >= v3.1.4024.42 (required)	PC or CX (x64, x86)	Tc3_PlasticBaseApplication (>= v12.10.2.0)