If I'm reading your description correctly then the parallel configuration should work as needed and there is no problem with both controllers being activated at the same time.

Thanks everyone for your thorough explanations. I now realize that the relays are a bit overkill, since even if both devices close the circuit, no harm can be done to the circuit (or devices). Now all I need to do is to try this

 

Thinking of the functioning of the locking system it would seem that the Electric Strike is energized, holding a door locked denying entry to all except those with the necessary key-card or radio-ID card. Therefore I surmise that the controller holds the relay active until someone with a key card deactivates the lock. The door remains locked at all times as Long as there is power. In the event of a power failure the doors will unlock and allow personnel to escape from a potential trap.

Now, I ask, is this the case? Is the door electrically held locked until a key card is presented?

 

Now, I ask, is this the case? Is the door electrically held locked until a key card is presented?

Not according to the TS.
See first paragraph in post #17

 

See first paragraph in post #17

Guess I don't know what an electrical striker is. Is it one of those things that buzz the door open?

Where I went on a tangent was thinking of those magnetic locks that when energized keep a door locked. If power is lost the lock fails open as a safety device. Having been redirected by post 17 I'm now thinking it's one of those locks where someone has to buzz you in - or a key card lets you buzz yourself in.

Either way, the parallel diagram suggests it will work.

Thanks sghioto for redirecting my thoughts on this thread.

 

Isee that there is a terrible lack of knowledge here. One claim is that the door is held locked electrically, which I have actually seen and even have such a device. The much more common device is an electrically released door strike, The "strike" being the part in the door frame that the bolt from the door lock mechanism strikes as it latches. The electromagnetic hold-closed system was used to stop grab-and-run thieves from exiting the store by means of holding the door closed. It is activated by a switch available to the store personell. It would not survive even one hour holding a door locked.
So we suffer from two different sources saying that their idea is the only correct one.

My concern is about all of those other terminals on the access control module shown in post #1. Certainly if the Common, N.O. and N.C. contacts are completely isolated, a simple parallel connection with another device will be all that is required.

 

I see no lack of knowledge as the lock was defined by the TS in post #17.

 

I'm still not sure what might happen if you swipe correctly 2 cards on both devices and they both close the circuit. Wouldn't it be a problem with the parallel setup?

It would not be a problem.

Already told you this.

 

The "lack of knowledge " was from those unfamiliar with electric latch-strike release systems,as found on quite a few apartment buildings, where multiple residences share a single entryway door that each resident can unlock (momentarily) remotely.