text: <user>
  Create a function block in TwinCAT Structured Text for managing variant-specific boot folders and restarting TwinCAT from HMI.<|endoftext|>
  <assistant>
  FUNCTION_BLOCK FB_VariantManager
  VAR_INPUT
      sVariantName : STRING;
      bRestartTwinCAT : BOOL;
  END_VAR
  VAR_OUTPUT
      bError : BOOL;
      sErrorMessage : STRING;
  END_VAR
  VAR
      fbAdsWrite : ADSWRITE;
      fbFileDelete : FB_FileDelete;
      fbFileCopy : FB_FileCopy;
      sSourcePath : STRING := 'C:\TwinCAT\3.1\Boot\';
      sDestPath : STRING := 'C:\TwinCAT\3.1\Target\Resource\Variants\';
  END_VAR
  
  // Main logic
  IF sVariantName <> '' THEN
      // Copy variant-specific boot folder
      fbFileCopy(
          sNetId := '', 
          sSourcePath := CONCAT(sSourcePath, sVariantName, '\_Boot'), 
          sDestPath := CONCAT(sDestPath, sVariantName),
          bExecute := TRUE
      );
      
      IF fbFileCopy.bError THEN
          bError := TRUE;
          sErrorMessage := CONCAT('Error copying variant folder: ', TO_STRING(fbFileCopy.nErrId));
      END_IF
  END_IF
  
  // Restart TwinCAT if requested
  IF bRestartTwinCAT AND NOT bError THEN
      fbAdsWrite(
          NETID := '', 
          PORT := 10000,
          IDXGRP := 16#F003,
          IDXOFFS := 16#0,
          LEN := 1,
          SRCADDR := ADR(bRestartTwinCAT),
          WRITE := TRUE
      );
      
      IF fbAdsWrite.ERR THEN
          bError := TRUE;
          sErrorMessage := CONCAT('Error restarting TwinCAT: ', TO_STRING(fbAdsWrite.ERRID));
      END_IF
  END_IF
  
  // Function block implementation
  // This function block manages variant-specific boot folders and TwinCAT restart
  // It copies the variant-specific _Boot folder to the Variants directory
  // and can trigger a TwinCAT restart via ADS
  
  // Related TwinCAT 3 features and programming techniques:
  // 1. ADS Communication: Used for restarting TwinCAT remotely
  // 2. File Operations: Utilized for copying variant-specific folders
  // 3. String Manipulation: Employed for constructing file paths<|endoftext|>
  