Took me a while to figure this out by trial and error:
If your frustrated when getting a com-exception like "Error [0x80004002] ..." (with a message nagging you about an unsupported interface), and you're calling a class method through COM that expects a char as an argument, you should NOT call the method with a single-character string.
The correct way of calling a method like this is to use a VARIANT with a type of VT_UI1.
COM enabled method definition:
public bool DoSomething(char arg);
<?php
$com = new COM('Some.Class.Name');
$var = 'a';
$com->DoSomething($var);
$var = new VARIANT(ord('a'), VT_UI1);
$com->DoSomething($var);
?>
I hope this helps some people
