@ UKHeliBob, there is no input for the relay contacts to connect to.
@ Riva when the PE beam is broken the relay contacts change state until the beam is unbroken (for the use of a better word). Usually it is momentary as people & vehicles pass thru it, but occasionally a vehicle parks in front of it which means the contacts stay closed / open. I can't remember which way it is wired.
@ GoForSmoke you are onto it, but how do I go about doing that please?
What / who is BWD/ I googled it but came up with no results?