character ASCII code in InstallScript InstallShield

Question

I want to keep user from entering character > ASCII 127 in one of the password field in installer.

I googled but didn't find any direct way for this, currently i'm using:

CHAR ch;
STRING ASCII;
NUMBER nASCII;

for nCount = 0 to StrLength(sPassword)
  ch = sPassword[nCount];
  sprintf(ASCII,"%d",ch);

  StrToNum(nASCII,ASCII);

  if ( nASCII > 127 )
    MessageBox("Invalid Character in Password",INFORMATION);
  endif; 

endfor;

Is there any better way to get ASCII code from a string?