OK found the error. Switch is ABB SA/S12.6.1 and should report either $00 closed or $01 open. However some of the switch reports status off as $2A and other correct $01 (on same unit with same basic parameters). If I manually write to that switch close, it updates to $00, but when reading it again it read the wrong $2A.
ABB brain is not available before monday, so I will try to ask him for a solution. SInce on 7 different units, there is no logic in when it reports corrct or wrong.
So I will revert when news