In my opinion, unless the owner of the system had previously agreed to the contrary, the owner of the system has all rights to the materials/codes/software (as provided at the date of supply) for any product that he purchases.
Even if he signed these rights away unknowingly, the contract could still be considered to include unfair terms by a court.
I know that we are all aware of times when justice is an 'ass' but the simple fact is a court of law would consider that someone buying something should have access to everything that is required to use that equipment correctly and would be deemed to have these rights upon purchase.
I guess this question arises because a company is witholding access control panel access codes from an owner of a system. I'm pretty sure the owner could win his case in court, but it could be easier and cheaper to try and find out the default codes in some way, as Greg C suggests, or to just replace the control panel!