In some buildings and industrial facilities, an elevator or hydraulic lift should only be operated by authorized users.
For example, a lift may have landing call buttons located in an area that is accessible to the public, visitors, workers, or other unauthorized people. In these situations, a password keypad or card reader can be used to control access to the elevator.
The basic principle is simple:
Only after a valid password or access card is verified can the elevator call button become active.
If the password is incorrect or the user does not have an authorized card, pressing the call button will have no effect.
What Is an Elevator Access Control Keypad?
An elevator access-control keypad is normally installed next to a landing call button.
Depending on the model, it may support:
Password entry
RFID cards
IC cards
Proximity cards
Other electronic access credentials
The keypad does not normally control the elevator motor, hydraulic pump, or valve directly.
Instead, it works as an access-control switch between the call button and the elevator control system.
This means the existing elevator controller can continue to handle the normal operating and safety functions.
How Does the Four-Wire System Work?
A common access-control keypad used for this application has four wires.
Two wires provide power to the device:
DC positive
DC negative
The other two wires are the relay output.
The device commonly uses a Normally Open (NO) dry contact for this output.
The basic connection can be understood as:
DC Power → Password Keypad
and
Keypad Relay Output → Elevator Call Button Circuit
When the user has not been authenticated, the relay remains open.
The call button circuit is therefore disconnected from the elevator controller.
After the user enters the correct password or presents an authorized card, the keypad activates its internal relay. The two signal terminals then become electrically connected.
The call button circuit is completed, allowing the button signal to reach the elevator control system.
In simple terms:
No authorization → Relay open → Call button inactive
Valid authorization → Relay closed → Call button active
Why Use a Normally Open Contact?
The Normally Open contact provides a simple way to prevent unauthorized operation.
Under normal conditions, the access-control device does not provide a connection between the call button and the elevator controller.
Only after successful authentication is the connection established.
This means the keypad is essentially providing permission to use the call button, rather than directly controlling the elevator.
For example, if a user enters an incorrect password:
Incorrect password → Relay remains open → Call signal cannot reach the controller
If the password is correct:
Correct password → Relay closes → Call button can send its signal to the controller
The exact relay operating time depends on the access-control device and its configuration.
Typical Applications
This type of access control can be useful when a lift landing is accessible to people who should not be able to operate the equipment.
Typical applications include:
Private Home Lifts
A home lift can be equipped with a password keypad or card reader so that only residents or authorized users can call the lift. If you are looking for a residential lifting solution, see our 2-Floor Home Lift (350kg Capacity) With Glass Shaft as an example of a system where access control can be integrated.
Warehouses and Industrial Facilities
For cargo lifts and hydraulic lifting platforms, access control can restrict operation to trained or authorized personnel.
Private Parking Areas
Vehicle lifts and parking systems can use access control to prevent unauthorized users from operating the equipment.
Publicly Accessible Landings
If an elevator landing is located in an area accessible from outside a building or facility, a password or card reader can provide an additional layer of operational control.
Password Access or Card Access?
Both methods can provide the same basic function.
Password access allows users to enter a predefined code. It is convenient for smaller installations, although passwords can potentially be shared.
Card access allows authorized users to present an RFID, IC, or proximity card. This can be more convenient when many users need individual access credentials.
The appropriate method depends on the application and the access-management requirements.
Access Control Is Not a Replacement for the Safety System
An important distinction is that access control and elevator safety are two different functions.
The password keypad determines whether a user is authorized to operate the call button.
The elevator control system remains responsible for the operation of the lift and its safety functions.
Depending on the equipment, these may include:
Emergency stop
Door or gate interlocks
Upper and lower limits
Safety edges
Light curtains
Hydraulic safety valves
Overload protection
PLC safety logic
Emergency lowering functions
The access-control device should therefore be integrated into the appropriate low-voltage control circuit without bypassing the required safety devices.
A Simple Control Structure
The complete concept can be summarized as:
Password / Card
↓
Authentication
↓
Access Granted
↓
Relay Contact Closes
↓
Call Button Enabled
↓
Elevator Controller Receives Call
↓
Safety Conditions Checked
↓
Lift Operates
If authentication fails, the relay remains open and the call button cannot provide an effective operating signal to the controller.
Conclusion
An elevator password keypad or card reader provides a simple method of restricting access to a lift.
A typical four-wire device uses two wires for 12–24V DC power and two wires for a Normally Open relay output.
The relay output is connected to the appropriate elevator call-button circuit. Without valid authorization, the relay remains open and the call button cannot effectively communicate with the elevator controller. After a correct password or authorized card is detected, the relay closes and the call button becomes active.
The key principle is:
The access-control device does not directly operate the elevator. It controls whether the user is permitted to send a call signal to the elevator controller.
This approach can be used for hydraulic lifts, home lifts, cargo lifts, industrial lifting platforms, parking lifts, and other applications where elevator operation needs to be restricted to authorized users. For a multi-floor residential application, our 4-Floor Home Lift (350kg Capacity) is one example where this type of access control is commonly specified.
For each installation, the actual keypad wiring, voltage, relay configuration, PLC input circuit, safety architecture, and applicable regulations should be verified according to the specific equipment and project requirements.
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