On your WIZ550WEB base board, you have I/O pins D8 - D11 routed to jumpers that can be used to select either a switch or an isolated input. In either case, these signals are pulled low.
I’ve learned the hard way that these signals do serve a function other than just inputs or outputs, but I can’t find those functions documented anywhere. D8 seems to have something to do with the way the module boots on power up. What happens if D8 is pulled up instead of down? What about the others?
Come on, guys. Please document these important functions so people don’t think they got a dead module just because an undocumented bit isn’t wired the way you want…