The drain wire is connect ONLY to the remote device; it is never connected on both ends, run in parallel or any other configuration.
For example,
Beginning at the Controller - there is NO drain connection anywhere.
At the Exit keypad the drain should ONLY be connected to it, and nowhere else.
At the Entry Keypad, the drain should ONLY be connected to it, and nowhere else.
At the Receiver, the drain should ONLY be connected to it, and nowhere else.
For example:
Starting at the Controller there is NO drain connection. The first keypad that the cable goes to (normally the exit) the drain from that leg of cable gets attached to that first keypad. It is terminated there.
From the first keypad to the next keypad (Likely the Entry keypad) there is no connection at the Exit (the first keypad) but it IS terminated at the second keypad (the entry).
In both cases, the drain is connected to the stud at the back of the keypad. Also attached to this stud is a cable/wire that goes to an Earth Ground rod/stake that is pounded into the ground.
So even though the power and data may be paralleled to each keypad, the drain wires are NEVER done that way. Doing so will cause a ground loop to occur which can create a voltage on one the other or both keypads.
