Should the push button connect to the open, single-button, exit, or three-button control input?
Use the input that matches the command you want. OPEN is usually best for a basic access button that should open or reopen the gate. SINGLE BUTTON cycles through multiple commands. EXIT is generally reserved for free-exit devices. A three-button input is for a dedicated OPEN-CLOSE-STOP station and requires the operator’s specified wiring and programming.
Choose the Input by Command Behavior, Not Terminal Location
A standard push button normally provides a momentary dry-contact closure. The control board decides what that closure means. Connecting the same button to OPEN, SINGLE BUTTON, EXIT, or a three-button station circuit can produce very different results.
Before wiring, identify the operator model, control-board revision, terminal labels, and programmed input mode. Some boards place these functions on a main terminal strip, while others require an expansion board, plug-in loop detector, selectable DIP switch, or manufacturer-specific control station. Do not assume similarly numbered terminals perform the same function across different operator families.
Use OPEN for a Basic Access or Entry Command
The OPEN, FULL OPEN, or OPEN ONLY input is usually the preferred connection for a basic push button, keypad relay, intercom relay, telephone entry relay, or access-control output. A momentary normally open contact generally opens a closed gate. On many operators, it also reverses a closing gate back toward the open position.
OPEN is usually the better choice when the person pressing the button should not be able to command the gate closed. Closure can then be handled by the operator’s automatic-close timer, a separate close device, or another documented control input. This is common at reception desks, access-control panels, resident entry stations, and security points where the button’s purpose is to grant entry.
A maintained OPEN signal may pause the automatic-close timer or hold the gate at the open limit on some boards. That behavior varies. A stuck relay, maintained switch, shorted cable, or moisture across the input can therefore make the gate open normally but refuse to close.
Use SINGLE BUTTON When One Control Must Cycle the Gate
SINGLE BUTTON may also be labeled SBC, STEP, START, CYCLE, or step-by-step. This input typically changes commands with repeated presses. A common sequence is open, stop, close, stop, although some boards use open-close-reverse or other programmed logic.
This input can be useful at a staffed station where one button must control the complete operating sequence. It is less appropriate for a public access button because a second press may stop or close the gate instead of simply granting entry. The exact response can also change with gate position, travel direction, timer status, or control-board programming.
Do not assume SINGLE BUTTON means open only. Some operators use the term for a cycling input, while others allow a transmitter button to be programmed as open-only or as open-close-stop. Verify the hardwired input description separately from wireless transmitter programming.
Reserve EXIT for Free-Exit Devices Unless the Manual Says Otherwise
An EXIT input is generally intended for a vehicle loop detector, probe, photoelectric vehicle sensor, request-to-exit device, or access-control relay used to release traffic from the secure side. Its normal purpose is to open the gate without requiring a resident credential.
A dry-contact push button may electrically activate an EXIT input when the manual identifies it as a standard normally open command. However, EXIT is usually not the first choice for a general wall button. The board may apply special logic such as vehicle-loop fault behavior, anti-tailgating, quick-close timing, hold-open while the detector remains active, or different priority during closing.
Some boards do not provide a separate hardwired EXIT terminal at all. They may use a plug-in detector socket, convert another terminal between full-open and exit-loop functions through a DIP switch, or route the loop detector output internally. Confirm whether the label refers to an input terminal, a detector port, or an output from a plug-in detector.
Use Three-Button Control Only for a Matched OPEN-CLOSE-STOP Station
A three-button control station gives separate manual commands for OPEN, CLOSE, and STOP. It normally requires more than two conductors and may use a shared common, normally open OPEN and CLOSE contacts, and a normally closed STOP circuit. The STOP circuit often overrides the other commands, so a missing jumper, broken wire, or incorrect contact can prevent all movement.
Use this connection when the operator specifically supports three-button control and the application requires independent directional control. Typical uses include guard stations, controlled commercial entrances, maintenance areas, and locations where an authorized operator must start, stop, or close the gate deliberately.
Some boards require a DIP-switch change, jumper position, programming selection, or manufacturer-matched station. A generic three-button station can malfunction if its internal common arrangement or STOP contact logic does not match the board. A single two-wire push button should not be landed randomly on one part of a three-button circuit.
Technician’s Corner
Technical Field Note: OPEN is usually the safest command for credentialed entry because another press cannot normally command a closing cycle. SINGLE BUTTON can close or stop the gate depending on its present state.
Technical Field Note: An EXIT input may look identical to OPEN during a quick test but behave differently when a loop remains occupied, a detector faults, anti-tailgating is enabled, or the gate reaches the open limit.
Technical Field Note: If a three-button station is added and the operator stops responding, check the normally closed STOP circuit first. An open STOP wire can override otherwise correct OPEN and CLOSE signals.
Technical Field Note: In South Florida humidity and salt-air exposure, water intrusion across OPEN or EXIT conductors can simulate a maintained command. Input LEDs that stay on after the button is released are a valuable diagnostic clue.
Technical Field Note: A command input does not replace entrapment protection. Required monitored photo eyes, sensing edges, inherent obstruction sensing, screening, and gate clearances must remain correct regardless of which activation terminal is used.
Before You Choose the Input
- Record the operator model, control-board part number, revision, and manufacture date.
- Confirm that the push button provides an isolated dry contact and does not send voltage into the board input.
- Decide whether the button should open only, cycle through commands, release exiting traffic, or provide separate OPEN-CLOSE-STOP control.
- Verify momentary or maintained action and normally open or normally closed logic.
- Check for DIP switches, jumpers, expansion boards, plug-in detector ports, and programmable input assignments.
- Confirm automatic-close timer behavior, command priority, loop logic, and line-of-sight requirements.
- Test input LEDs and verify that all monitored safety devices remain recognized and functional.
Related Technical Categories
- Push Buttons and Control Stations
- Gate Operator Control Boards
- Access-Control Relays and Receivers
- Vehicle Loop Detectors and Exit Sensors
- Key Switches and Telephone Entry Controls
- Gate Safety Devices
For most basic access applications, connect a momentary normally open dry-contact button to the documented OPEN or FULL OPEN input and its matching common. Use SINGLE BUTTON only when cycling behavior is intended, EXIT for the operator’s approved free-exit logic, and three-button terminals only with a compatible OPEN-CLOSE-STOP station. Verify model number, part number, voltage, contact type, connector layout, and operator generation before selecting or wiring replacement hardware.