FB_TcTouchLock_AcquireFocus

The FB_TcTouchLock_AcquireFocus function block is used to prevent parallel, interfering inputs via several multi-touch control panels connected to one IPC. To this end, the focus is placed on one of the connected control panels, while inputs from all other connected control panels are blocked. The FB_TcTouchLock_AcquireFocus function block can be used to request and release the focus.

If the focus is requested from a multi-touch control panel when another multi-touch control panel currently has the focus, the focus must first be released by this panel. Once the release has taken place, the focus is automatically set to the device that is waiting for it.

The multi-touch control panels that are accessed by the function block must first be configured using the command line application TcTouchLockService.exe. Each device must be assigned a specific identification number.

Inputs

VAR_INPUT
    bEnable    : BOOL;
    sSetID     : STRING(32);
    tLEDTime   : TIME := 200;
END_VAR

Name	Type	Description
bEnable	BOOL	TRUE = request focus, FALSE = release focus
sSetID	STRING	ID of the device
tLEDTime	TIME	The output LED flashes at the specified interval (100 ms – 1 s) while the focus is requested.

Outputs

VAR_OUTPUT
    bAcquired  : BOOL := FALSE;(* Focus status information *)
    bLED       : BOOL := FALSE;(* LED control output *)
    bBusy      : BOOL;(* TRUE => function in progress *)
    bError:    : BOOL;(* Error flag *)
    nErrID     : UDINT;(* Error code *)
END_VAR

Name	Type	Description
bAcquired	BOOL	TRUE if the client has the focus; FALSE if the client loses the focus.
bLED	BOOL	This output has the following meaning, depending on the mode:

Mode	Meaning
Constant TRUE	The panel has the focus
Constant FALSE	The panel does not have the focus
Toggeles	The panel is waiting for the focus

Name	Type	Description
bBusy	BOOL	When the function block is enabled, this output is set and remains set until a feedback is received.
bError	BOOL	If an error should occur during the transfer of the command, then this output is set once the bBusy output was reset.
nErrId	UDINT	Returns the ADS error number or the specific function block error number if the ERR output is set.

Error codes	Error description
0x0000	No error
0x0006	Target port not found

Example: control of touch focus via special key

Manual setting of the focus can be controlled via a special key on the panel, for example. As the focus should also be requested via the touch screen when the input is locked, an input option outside the lockable touch screen must be considered. The special key is linked to the corresponding input variable in the PLC program through the TwinCAT System Manager. One FB_TcTouchLock_AquireFocus instance is created per panel and configured with the panel ID. After pressing the special key on a panel, the function block R_TRIG detects the rising edge, and the PLC program tries to set the touch focus via the corresponding FB_TcTouchLock_AquireFocus instance. The function block can also control an output (e.g. an LED), which signals whether the touch focus has been set successfully or whether an attempt is still being made to obtain the focus. Pressing the special key again resets the touch focus, allowing the touch focus to be set to another panel.

For two panels the PLC program looks like this:

PROGRAM MAIN
VAR 
    button1 AT%IX0.0 : BOOL; 
    button2 AT%IX0.1 : BOOL; 

    led1 AT%QX0.0 : BOOL; 
    led2 AT%QX0.1 : BOOL; 

    fbPanel1 : FB_TcTouchLock_AcquireFocus := ( sSetID := 'A' ); 
    fbPanel2 : FB_TcTouchLock_AcquireFocus := ( sSetID := 'B' ); 

    trigger1 : R_TRIG; 
    trigger2 : R_TRIG; 
END_VAR

(* Panel 1 *)
trigger1( CLK := button1 ); 
IF trigger1.Q THEN
fbPanel1.bEnable := NOT fbPanel1.bEnable; 
END_IF
fbPanel1(bLED=>LED1); 

(* Panel 2 *)
trigger2( CLK := button2 ); 
IF trigger2.Q THEN
fbPanel2.bEnable := NOT fbPanel2.bEnable; 
END_IF
fbPanel2(bLED=>LED2 );

Requirements

Development environment	Target platform	PLC libraries to be integrated (category group)
TwinCAT v3.1. >= 4022.31	PC or CX (x86, x64)	Tc2_IoFunctions (IO)