Does anyone know if Emerson makes PLC and is there any model that is equivalent to AB SLC 500 series? I am not even sure they produce PLC ...

There's PLC functionality inside Emerson's Control Techinques AC & DC drives using add-on modules. I don't really think it's comparable to the SLC500, but it's probably good for small applications where you already need the drive. Haven't used the PLC functions myself, but I've got a couple of the Commander SK drives and know that it's there if I ever do need it.

HTH!