IR543 and X10 Codes
Does the IR543 work with all 16 unit codes, or is it only 1-8?
Unit Codes 1 through 8 can be controlled from the keypad on the IR543.
Codes 1-10 can be controlled from an X10 IR remote (they don't support double digit entry and so can't do 11-16, but 10 is the 0 button on the remote).
Some third-party remotes can send IR signals at 11-16; you can control all 16 Unit Codes with an IR543 if you have one of these remotes.