February 5, 2003 1

Inputs and Output Relays

February 5, 2003 2

What are Inputs and Output Relays?

• Inputs allow the controller to receive signals from the outside world

• Output Relays allow the controller to turn on or off external devices

February 5, 2003 3

Input Definition

• A point on the controller which detects a state change generated by an outside device– Typically some kind of switch

• The controller then performs some action based on programmed instructions

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Normally-Closed Input

• A normally-closed switch generates a state change by opening a normally-closed input circuit

• A typical normally-closed input application is a Door Status switch

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Normally-Open Input

• A normally-open switch generates a state change by closing a normally-open input circuit

• A typical normally-open input application is a Request to Exit device

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Input Types

• The PXL-500 can accept any of four programmed input signals:– Door Status– Request to Exit– General Purpose

• The controller responds to input signals according to programmed instructions

February 5, 2003 7

Door Status Input

• A normally-closed input, it reports the status of the door: open or closed– If the status is “forced

open,” the controller can respond with a Door Forced alarm

– If the status is “open too long,” the controller can respond with a Door Held Open alarm

February 5, 2003 8

Request to Exit (RTE) Input

• A normally-open input, it reports a user request to exit through a secure door– The controller can

unlock a secure door to allow exit

February 5, 2003 9

Global Unlock Input

• A normally-open input, it reports a request to unlock all doors immediately– The controller can send a

signal to all controllers to unlock all secure doors, allowing exit

February 5, 2003 10

General Purpose Inputs

• If you need General Purpose inputs, consider using an SB-593 Satellite Board

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General Purpose Inputs

• Can be either normally-open or normally-closed inputs, an input reports a change of state– The controller must be

programmed with instructions on how to respond to the state change

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Output Relay Definition

• A point on the controller that changes state to initiate an action outside of the controller

• An output relay is driven by programming instructions within the controller

February 5, 2003 13

Output Relay Definition

• Keri controllers use Form C relays– Single-pull, double-throw (SPDT)– Drive either normally-open and normally-closed circuits– Energizing the coil toggles the relay common from

normally-closed to normally-open

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Output Types

• The PXL-500 can output a state change to any of two programmed output types– Door Lock Relay– Alarm Relay

• An optional SB-593 Satellite Board adds other output types– Door Held Open Relay– General Purpose Relay

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Door Lock Relay

• Unlocks a door when activated

• Can use either the normally-closed or normally-open output circuits– depends upon the level

of safety versus security: Fail-safe versus Fail-secure

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Fail-safe Lock Application

• Requires power to keep doors locked, doors are unlocked if the power fails

• Typically uses a normally-closed circuit with magnetic door locks for operation

• When the relay is activated:– The normally-closed circuit is opened– Power to the door lock is dropped– The door can now be opened

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Fail-safe Lock Circuit

• Since doors require power to be locked, if the power fails, doors are automatically unlocked

• Allows safe exit in power failure situations, but security may be compromised

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Fail-secure Lock Application

• Requires power to unlock doors, doors are locked if power fails

• Typically uses the normally-open circuit for operation

• When the relay is activated:– The normally-open circuit is closed– Power is applied to the door lock– The door can now be opened

February 5, 2003 19

Fail-secure Lock Circuit

• Since doors require power to be unlocked, if the power fails, doors cannot be unlocked

• Provides security in power failure situations, but safety may be compromised

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Alarm Relay

• Used to activate an alarm when a door’s security is violated

• Typically uses the normally-open output circuit– when the relay is

activated, the normally-open circuit is closed

– closing the circuit allows an alarm to sound

February 5, 2003 21

Additional Relay Outputs

• Available on the SB-593 Satellite Board

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Door Held Open/Door Forced Relays

• Activates an alarm when – A door is held open past a

defined time– A door is forced open

• Typically a normally-open output circuit, when activated, the normally-open circuit is closed, providing power to sound an alarm

February 5, 2003 23

General Purpose Relays

• Either normally-open or normally-closed output circuits can be used

• External equipment that will respond to the state change is connected to the relay output

• The controller is then programmed with instructions on when to generate a general purpose relay state change