[GreenKeys] Model15 keyboard wiring?

[steve bennett]

GKs,

 Greetings. John Lawson was kind enough to send me a keyboard for my model 15 and
I am trying to figure out how to wire it.
My machine is a RO and is not equipped with the electrical contacts for the keyboard.

I thought it would just be wired in series with the printer but apparently I was wrong.
The keyboard is an open circuit when in the idle state and when a key is pressed contacts in the
mechanism close in sequence to produce the code.
Exactly the opposite of what I was thinking it would do.
If I wire the keyboard in parallel with the printer it will appear as a short circuit to the loop supply
when contacts close so it would effectively shunt the selector magnets and short out the loop supply.
(My loop is a Flesher TU170)

That does not sound safe.
Can someone explain how this is supposed to work? Do I need at add a current limiter to the keyboard or does
it do it's own current limiting?

And does polarity matter?

Thanks,
-Steve