How to sound a buzzer when a Request To Exit (REX) button is pressed?

[Product_Support]

Issue

How to sound a buzzer when a Request To Exit (REX) button is pressed on a Continuum Access system? The inputs to a door are not defined as regular Infinity inputs so how can they be programmed by Plain English programming?

Environment

ACX57xx (ACX5740, ACX5720) and AC-1 IOU modules (AC-1, AC-1A, AC-1 Plus)

Cause

When engineering an access control project, there is sometimes the requirement to sound a buzzer or turn on a light when the door is unlocked, or when a Request To Exit button is pressed, as the input points used within the door object configuration are not defined as a regular Infinity Inputs, so how to achieve this functionality?

Resolution

To use a Request To Exit (REX) switch on any of the ACX controllers or AC1 Modules:

1.  It has to be a supervised input wired with the appropriate resistors in one of the 6 standard configurations defined in the installation guides (All available on the Extranet).
2. You can not use a simple digital input switch without resistors.
3. Incorrect circuitry or missing resistors will result in a Trouble indication on the door.
4. The REX input is not a regular Continuum input point as it is defined within the door configuration, as it is not a Infinity input point directly accessible from Plain English but can be read via the "ExitRequest" attribute of the door.

To sound a buzzer from the from the door there are 3 options:

1. Use the existing door output and slave a buzzer circuit from the output that drives the Magnetic lock, so will sound when the door unlocks.
2. If you want the buzzer to sound when the REX button is pressed then use a button with a 2 pole switch (2 separate contacts):
   1. Wire one to the REX input with appropriate resistors.
   2. Wire the other switch to a spare Input
   3. Configure it as either a Digital input or a Supervised input with resistors.
   4. This point can be used in your PE programming to drive the buzzer output.
3. The third option is to use a Plain English program to read the "ExitRequest" attribute of the door and turn on an output for a defined time. The ExitRequest attribute may only be on for a short period of time so the program must be constantly looking for this attribute to change as well as keeping the controller Scan time low.