Purpose

This guide explains how to connect a ButterflyMX intercom to a ButterflyMX 2-Door Controller so that the intercom can trigger door unlocking through the controller's Request to Exit (REX) input. In this configuration, the intercom uses a dry-contact relay output to simulate a Request to Exit event on the 2-Door Controller. When the intercom unlock command is triggered, the relay closes the circuit between COM and NO, sending a signal to the controller's REX input. The controller then interprets that closure as a valid REX event and unlocks the door according to its programming.

Prerequisites

1. ButterflyMX intercom installed and powered on
2. ButterflyMX 2-Door Controller installed and powered on
3. Door lock hardware is already connected to the 2-Door Controller
4. Access to the terminal blocks on both devices
5. Appropriate low-voltage wiring available (for example, 18/2 or 22/2)
6. Basic understanding of low-voltage access control wiring

Procedure

Step 1: Identify the relay output on the intercom

1. Locate the relay output terminals on the ButterflyMX intercom.
2. These terminals are typically labeled COM (Common), NO (Normally Open), and NC (Normally Closed).
3. For this integration, COM and NO are the required relay terminals.

Step 2: Identify the correct REX terminals on the 2-Door Controller

1. Locate the REX input section for the door you are integrating on the 2-Door Controller.
2. For Door 1, use the terminals labeled REX and SNS in the REX 1 section.
3. For Door 2, use the terminals labeled REX and SNS in the REX 2 section.
4. Do not apply voltage to the REX input. It expects a dry contact closure only.

Step 3: Prepare the low-voltage wiring

1. Use a suitable low-voltage cable, such as 18/2 or 22/2, based on site standards and distance.
2. Strip the wire ends cleanly and ensure all conductors are secured properly in the terminal blocks.
3. Label the cable where possible to simplify future maintenance and troubleshooting.

Step 4: Make the physical relay-to-REX connection

1. Connect the intercom COM to the controller SNS (the common reference for the REX input).
2. Connect the intercom NO to controller REX.
3. This wiring arrangement allows the intercom relay to close the REX circuit when an unlock command is issued.

Step 5: Verify relay configuration on the intercom

1. Confirm that the relay being used by the intercom is configured for Normally Open operation.
2. If configurable, confirm that the relay activation duration is sufficient for the controller to register the REX input. A short momentary trigger is usually sufficient, but site configuration may vary.

Step 6: Test the unlock sequence

1. Initiate a call or unlock action from the intercom.
2. Trigger the unlock command through the ButterflyMX app or the configured intercom workflow.
3. Verify that the controller receives the REX event and unlocks the door.

Step 7: Confirm consistent door behavior

1. Test the sequence multiple times to ensure repeatable performance.
2. Confirm that there is no intermittent triggering, excessive delay, or missed unlock event.
3. Document the final wiring and the door used for the integration.

Wiring Summary

The intercom relay provides a dry contact closure that simulates a Request to Exit (REX) input on the access control system.

Reference Image

The image below identifies the terminal layout of the ButterflyMX 2-Door Controller. For Door 1 integrations, the relevant REX section is located on the lower left side of the controller and is labeled REX 1 with terminals REX and SNS.

Figure 1. ButterflyMX 2-Door Wiring drawing

Troubleshooting

Door does not unlock: Recheck the wiring between intercom COM and controller REX, and between intercom NO and controller REX. Confirm that the intercom relay is actually closing when the unlock event is triggered.

Door unlocks intermittently: Inspect for loose conductors, poor cable terminations, or relay timing that is too short. Retest after securing the wiring and confirming relay duration settings.

Controller does not detect the REX event: Verify that the controller input is expecting a dry contact closure and that no external voltage has been applied to the REX input. Use a meter to confirm continuity across COM and NO during relay activation.

Best Practices

1. Use labeled low-voltage cabling and maintain clean cable routing.
2. Keep signal wiring away from high-voltage lines whenever possible.
3. Do not share power across devices unless explicitly required by the design.
4. Record the final wiring path and relay used for future support reference.

Additional Notes

1. This integration is hardware-based and does not rely on API or cloud-triggered unlocking between the two devices.
2. The exact unlock response depends on the controller programming and door hardware configuration.

For deployments using Door 2 instead of Door 1, use the corresponding REX 2 section and its REX and SNS