A complete wiring and configuration guide for two-unit residential buildings, duplexes, and small apartment projects.

When a building has two units—whether it is a duplex, a two-family home, or a small apartment property—the intercom system needs to do one simple thing well: let each unit answer its own door calls independently. A 2-button outdoor station paired with 7-inch indoor monitors is the ideal solution. It gives each unit its own call button, its own indoor monitor, and its own unlock control—without the complexity or cost of a larger system.

FARHD has been manufacturing 2-wire video intercom systems since 1998. This guide covers the wiring, configuration, and testing of a 2-button outdoor station with 7-inch indoor monitors, using the simple and reliable 2-wire connection.

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Why 2-Wire for a Two-Unit Building?

The 2-wire system uses a single pair of standard two-core wires to transmit power, audio, video, and control signals. It is non-polarity, meaning you can connect the wires either way without risk of damage.

Key advantages:

• Installazione semplice – any electrician can complete the wiring.
• Reuses existing cabling – ideal for retrofits and older buildings.
• Up to 100 metres transmission – enough for most residential entrances.
• Economicamente vantaggioso – lower material and labour costs.
• Reliable – no network dependency, no Wi-Fi dropouts.

For a two-unit building, the 2-wire system is the most practical choice.

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System Components

A typical 2-button 2-wire kit includes:

Componente	Role
2-Button Outdoor Station	Two call buttons, one for each unit. Includes camera, microphone, speaker, and card reader (optional).
7″ Indoor Monitors	One per unit. Answer calls, view video, unlock door.
2-Wire Switch / Distributor	Optional. Distributes signal to multiple monitors. Recommended for reliable performance.
Alimentazione	15V DC adapter or central power supply.
2-Core Cable	Non-polarity, ≥0.5mm², up to 100m per run.
Electric Lock	Controlled by relay output. Requires separate 12V DC power supply.

The 7-inch indoor monitors feature IPS touchscreens, 1024×600 resolution, and support for two-way audio, video, and unlock control.

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Wiring Topology Options

There are two common ways to wire a 2-button system.

1. Direct Bus Wiring (Simplest for Two Units)

The outdoor station connects directly to the two indoor monitors via a shared 2-wire bus.

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[Outdoor Station] ── 2-wire ── [Indoor Monitor 1] ── 2-wire ── [Indoor Monitor 2]

Vantaggi:

• Fewer components—no switch required.
• Simple wiring for short distances.

Considerations:

• Each monitor must have a unique room number.
• A fault on the bus can affect both units.
• Maximum distance and number of monitors may be limited by the outdoor station’s power output.

Ideale per: Small buildings with short cable runs and only two units.

2. Star Wiring with 2-Wire Switch (Recommended)

The outdoor station connects to a 2-wire switch, and each indoor monitor connects independently.

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[Outdoor Station] ── 2-wire ── [2-Wire Switch] ── 2-wire ── [Indoor Monitor 1]
                                                   └── 2-wire ── [Indoor Monitor 2]

Vantaggi:

• Fault isolation—one unit’s issue does not affect the other.
• Easier room number configuration.
• Supports future expansion (additional monitors or outdoor stations).

Ideale per: Most two-unit installations, especially where reliability and future expansion matter.

Raccomandazione: Use a 2-wire switch for star wiring. It provides stable power distribution and simplifies troubleshooting.

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Step-by-Step Wiring Guide

Step 1: Mount the Outdoor Station

• Mount at 1.5–1.8 metres above ground.
• Avoid direct sunlight and heavy rain exposure.
• Use the included rain cover and mounting bracket.

Step 2: Mount the Indoor Monitors

• Mount each 7-inch monitor in a convenient indoor location (hallway, living room, or bedroom).
• Recommended height: 1.2–1.4 metres.
• Ensure there is a power outlet nearby if the monitor requires an adapter.

Step 3: Run the 2-Wire Cables

• Use 2-core cable (≥0.5mm²).
• Keep cable runs under 100 metres. For longer distances, use thicker gauge (0.75mm² or 1.0mm²).
• Avoid running cables parallel to AC power lines to prevent interference.

Step 4: Connect the Outdoor Station

• Connect the 2-wire cable to the outdoor station’s terminals. Polarity does not matter.
• If an electric lock is used, connect the lock wires to the relay output (NO and COM).
• A separate 12V DC power supply is required for the lock.

Step 5: Connect the 2-Wire Switch (If Used)

• Connect the cable from the outdoor station to the switch’s input.
• Connect each indoor monitor’s cable to the switch’s output ports.
• Power the switch with the supplied adapter.

Step 6: Connect the Indoor Monitors

• Connect each monitor’s 2-wire cable to the switch output or bus.
• Ensure each monitor receives power via the 2-wire connection.

Step 7: Power On and Test

• Power on the system.
• Press button 1. Indoor Monitor 1 should ring.
• Press button 2. Indoor Monitor 2 should ring.
• Test two-way audio, video, and unlock function.

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Configuration: Room Numbers and Button Mapping

After wiring, each indoor monitor must be assigned a unique room number, and each button on the outdoor station must be mapped to the correct unit.

Step 1: Assign Room Numbers to Indoor Monitors

Via Indoor Monitor Menu:

1. On the 7-inch monitor, enter the Settings menu.
2. Seleziona Room Number o Address Setting.
3. Enter the apartment number (e.g., 101 for Unit 1, 102 for Unit 2).
4. Save and exit.
5. Repeat for the second monitor.

Importante: Each monitor must have a unique room number. Duplicate numbers will cause both monitors to ring at the same time.

Step 2: Map Outdoor Station Buttons to Units

For a 2-button station:

• By default, Button 1 calls Unit 1, Button 2 calls Unit 2.
• If your numbering is different (e.g., 101 and 102), configure the mapping.

Configuration methods:

• Via indoor monitor menu: Some systems allow button mapping from the monitor’s settings.
• Via DIP switches or jumpers: Some models use physical switches on the outdoor station to set button addresses.
• Via management software: For advanced systems, assign each button to a specific room number.

Example mapping:

Pulsante	Unit	Room Number
1	Unit 1	101
2	Unit 2	102

Label each button with the resident’s name or unit number for easy identification.

Step 3: Configure System Settings

• Unlock duration: Set the relay release time (typically 3–10 seconds).
• Ringtone volume: Adjust indoor monitor ringtone volume.
• Video settings: Adjust brightness, contrast, and night vision if available.
• Language: Select the preferred language for the UI.

Step 4: Optional App Configuration (Tuya / Smart Life)

If the 7-inch indoor monitor supports Wi-Fi and Tuya Smart Life:

1. Connect the monitor to a 2.4GHz Wi-Fi network.
2. Download the Tuya Smart or Smart Life app.
3. Create an account and tap “Add Device.”
4. Follow the pairing instructions.
5. Assign the device to a room and name it (e.g., “Unit 1”).
6. Test remote answering, live view, and unlock.

Nota: Not all 2-wire systems support app integration. Check your specific model’s specifications.

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Testing and Commissioning

After configuration, test every function:

Test	What to Verify
Button 1 call	Rings Indoor Monitor 1 within 1.5 seconds.
Button 2 call	Rings Indoor Monitor 2 within 1.5 seconds.
: Fornisce filmati video dei visitatori.	Clear conversation, no echo, no dropouts.
Qualità video	Clear image, correct viewing angle, night vision activates in low light.
Unlock function	Door releases reliably; relay click audible.
Funzioni app	Remote answer, live view, and unlock work over Wi-Fi (if supported).

If any test fails, check wiring connections, cable continuity, and power supply voltage before replacing hardware.

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Risoluzione dei problemi comuni

Problema	Possibile causa	Soluzione
Both monitors ring at once	Duplicate room numbers	Assign unique numbers to each monitor
Button does not ring correct monitor	Button mapping incorrect	Reconfigure button mapping
No video	Loose cable	Re-seat 2-wire connections
No audio	Volume muted	Check volume settings
Unlock fails	Relay wiring	Verify lock power and relay connections
App not connecting	Wi-Fi on 5GHz	Switch to 2.4GHz network
Monitor does not power on	Insufficient power	Check 2-wire switch power supply

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Best Practices for 2-Button Systems

• Use quality cable – ≥0.5mm² copper for 2-wire runs.
• Keep cable runs under 100 metres – for longer distances, use thicker gauge or a repeater.
• Avoid parallel runs with power lines – prevents interference.
• Label both ends of every cable – simplifies maintenance.
• Test each unit after configuration – call from the outdoor station and verify all functions.
• Secure outdoor connections – use waterproof gel caps or silicone.
• Document room numbers and wiring – essential for future service.
• Update firmware – check for updates after installation.

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Why Choose FARHD for Your 2-Wire System?

FARHD has been designing and manufacturing video intercom systems since 1998, with over 28 years of industry experience. Our 2-wire systems are trusted in over 100 countries for their reliability, ease of installation, and robust feature set.

Key advantages:

• Source factory – Factory-direct pricing, full quality control.
• 2-wire simplicity – Reuses existing wiring, non-polarity, up to 100m.
• 7-inch indoor monitors – IPS touchscreen, clear video, responsive touch.
• 2-button outdoor station – Ideal for duplexes and two-unit buildings.
• Room number configuration – Flexible, supports 1–4 digit numbers.
• Resistente alle intemperie – IP65 outdoor stations, -40°C to +70°C.
• OEM/ODM/SKD – Custom branding, packaging, and software.
• No MOQ – Start with a sample; scale as you grow.
• Certificazioni globali – CE, FCC, RoHS, IP65, EMC.

Our products are installed in thousands of apartments, villas, and residential projects worldwide.

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Frequently Asked Questions

Q: Can I connect two indoor monitors directly to a 2-button outdoor station without a switch?
A: Yes, for short distances and simple installations. However, using a 2-wire switch is recommended for better reliability and fault isolation.

Q: How do I assign which button calls which monitor?
A: Configure room numbers on each indoor monitor and map the outdoor station buttons accordingly. Most systems default to Button 1 = Unit 1, Button 2 = Unit 2.

Q: What happens if both monitors have the same room number?
A: Both will ring at the same time. Always assign unique room numbers.

Q: Can I add a third indoor monitor later?
A: Yes, if the system supports expansion and you use a 2-wire switch with available ports.

Q: Does the system work without internet?
A: Yes. Basic calling, video, and unlock functions work without internet. Internet is only required for remote app access.

Q: What is the maximum cable distance?
A: Up to 100 metres with ≥0.5mm² cable. For longer distances, use thicker gauge or a repeater.

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Contact Us for Catalog, Pricing, and Samples

The FARHD 2-button outdoor station with 7-inch indoor monitors is the ideal choice for two-unit residential buildings. With easy 2-wire wiring, simple configuration, and reliable performance, it delivers everything you need for secure, convenient entry.

Contact us today for catalog, pricing, or to request a sample.

📩 Email: [email protected]
🌐 Website: www.farhd.com
📱 WhatsApp: +86 188 2370 9809 / +86 199 2545 1918

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FARHD – Video Intercom Manufacturer Since 1998.

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