How to use the root variable of the HMI Editor?

FAQ #100484

 

The Root Variable
The root variable shows the content of the register S.HMI.ROOTVARx on the root menu in the defined format. For using this root variable, click the button "Edit Root Menu" in the "Menu Structure" tab and select the standby menu "Custom Standby".
After the next build, you will see the system Symbol S.HMI.ROOTVARx in the symbol table of this CPU. The value of this register will be shown in the root menu.

 

The Root Variable ASCII
This kind of root variable will show the 4 bytes of the register S.HMI.ROOTVAR3 or 4 in ASCII format. This allows displaying short texts (4 characters).
The user has to define this bytes in the register in his program (it is not possible editing the text directly in ASCII).
If the test has to change (e.g. depending on an application status), the different characters are to be loaded accordingly. The screenshot below shows a possible fupla program that changes the content of the S.HMO.ROOTVAR4 based on the value of the register "TextSelector".
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All characters used are defined as K-constants in ASCII representation (hex format in this example but can also be the corresponding decimal value).
The register "TextSelector" selects the character at the inputs of the "Mux integer selection" FBoxes (standard family "Integer") that is written to the output of these FBoxes.
The FBox "Move-in Byte" (standard family "Move-In / -Out") finally assembles the four selected characters (in four different registers) into the register S.HMI.ROOTVAR4. This register can be displayed in the HMI Root display.