IP Camera KNX Integration via Relay Output: Wiring, Binary Input Modules and Alarm Group Addresses
Most professional IP cameras include one or more built-in relay outputs — dry contact or 12/24V outputs that switch on motion detection, video loss or tampering events. Wiring these relay outputs to KNX binary input modules bridges the gap between the IP video world and KNX building automation without requiring any network middleware.
Camera relay output types
IP camera relay outputs come in three common variants, each requiring a different wiring approach at the KNX binary input module. Understanding which type the camera provides determines the correct input module configuration.
| Output type | Signal | Wiring to KNX binary input | Typical cameras |
|---|---|---|---|
| Potential-free (dry) contact | NO/NC relay contact, no voltage | Direct to binary input terminals — input provides wetting voltage internally | Mobotix M73, Axis P3245, Bosch FLEXIDOME |
| 12V DC output | 12V on alarm, 0V idle | Via resistor or voltage divider if input max is 12V; check input spec | Hanwha QNV-8080R, Hikvision DS-2CD |
| 24V DC output | 24V on alarm, 0V idle | Connect directly if binary input accepts 24V AC/DC; confirm polarity | Axis P1375, Sony SNC series |
Always verify: consult the camera installation manual for the relay output section before wiring. Relay contact ratings vary — maximum switching current is typically 100–500 mA at 24V DC. The KNX binary input wetting voltage must not exceed the camera relay contact rating.
MDT SCN-8V.01 terminal wiring
The MDT SCN-8V.01 is an 8-channel KNX binary input module with configurable input mode per channel — voltage-free contact or 24V AC/DC voltage input. This flexibility makes it the preferred choice for camera relay integration where mixed output types may be encountered across cameras on the same panel.
MDT SCN-8V.01 wiring configuration
Terminal block layout (per channel pair): Terminal I+ → camera relay terminal A (or 24V+) Terminal I− → camera relay terminal B (or 24V−) Terminal V+ → internal 24V bus (used for voltage-free mode) Voltage-free contact mode (DIP switch per channel = OFF): Camera NO contact → I+ and I− directly MDT provides internal 12V wetting voltage Contact closed (alarm) → module reads HIGH → sends DPT 1.001 = 1 24V DC input mode (DIP switch per channel = ON): Camera 24V+ output → I+ Camera 0V (GND) → I− Voltage present (alarm) → module reads HIGH → sends DPT 1.001 = 1 Maximum cable length: 100m for voltage-free, 300m for 24V input Cable: 0.5mm² unshielded twisted pair sufficient for relay signals
Gira 1067/1068 alternative
- Gira 1067 00: 4-channel binary input, voltage-free only
- Gira 1068 00: 4-channel, 24V AC/DC input mode
- Same terminal labelling: E1+/E1− per channel
- ETS parameters identical: edge detection, debounce time
Debounce time setting
- Set debounce to 50–100ms for camera relay outputs
- Prevents false triggers from relay contact bounce
- ETS6: Input channel → Debounce time → 50ms
- Longer debounce (200ms) for noisy industrial environments
ETS6 group address assignment for alarm signals
Each camera relay output connects to one binary input channel, which maps to a KNX group address. The alarm GA structure should follow a systematic area/line/device convention that identifies the camera, alarm type and zone clearly for both ETS6 programming and future maintenance.
Recommended alarm GA structure
Area 8 = Security/CCTV alarms 8/0/x — Camera motion alarms 8/0/1 → CAM-01 Entrance motion alarm (DPT 1.001) 8/0/2 → CAM-02 Car park motion alarm (DPT 1.001) 8/0/3 → CAM-03 Server room motion alarm (DPT 1.001) 8/0/4 → CAM-04 Reception motion alarm (DPT 1.001) 8/1/x — Camera tamper alarms 8/1/1 → CAM-01 Tamper alarm (DPT 1.001) 8/1/2 → CAM-02 Tamper alarm (DPT 1.001) 8/2/x — Video loss alarms 8/2/1 → CAM-01 Video loss (DPT 1.001) 8/2/2 → CAM-02 Video loss (DPT 1.001) 8/3/0 → Alarm armed status (global arming GA) (DPT 1.001) 8/3/1 → Alarm acknowledge (DPT 1.001) Binary input channel ETS6 parameters: Object type: 1-bit DPT 1.001 Send on rising edge: YES (alarm start) Send on falling edge: YES (alarm cleared) Cyclic sending: NO (alarm is event-driven)
KNX logic for alarm response
Receiving a motion alarm GA value is only the input. The KNX system must react usefully — triggering a DALI lighting scene for the affected zone, activating an alarm horn and sending a notification email via ARISTO BewO. The logic gate structure also handles arming status so alarms during occupied hours do not trigger the siren.
MDT Logic Module alarm response chain
Alarm trigger condition:
IF GA 8/0/1 (CAM-01 Motion) = 1
AND GA 8/3/0 (Alarm Armed) = 1
→ Fire alarm response sequence
Response actions (parallel execution):
1. DALI lighting scene:
→ Write scene 4 ("Security Alert") to DALI GA 3/0/10
→ Zone 1 (entrance): 100% brightness, full white (4000K)
→ 10-minute auto-restore timer → scene 1 (standby 30%)
2. Alarm horn:
→ Write 1 to KNX binary output GA 8/4/0
→ Binary output relay → alarm horn 24V circuit
→ 30-second maximum ON timer (ETS6 staircase function)
3. ARISTO BewO notification:
→ BewO monitors GA 8/0/1 and GA 8/3/0 via KNX
→ Email: "Motion alarm CAM-01 Entrance" + timestamp
→ SMS (if GSM module fitted): same message
Alarm cleared (GA 8/0/1 = 0):
→ Horn OFF immediately (write 0 to GA 8/4/0)
→ DALI scene remains until acknowledge GA 8/3/1 = 1Arming logic: GA 8/3/0 (Alarm Armed) should be driven by the access control system — active when the last person has left (door locked + presence detector = 0 for 5 minutes). KNX logic modules can implement this armed/disarmed state machine without requiring a separate alarm panel.
Arming and disarming with KNX binary output enabling
A KNX binary input can be selectively enabled or disabled by linking its object enable function to the alarm armed GA. This approach means that when the system is disarmed, binary input channels connected to camera relays simply do not forward their status to the alarm GAs — eliminating false alarm logic complexity.
Input channel enable/disable in ETS6
MDT SCN-8V.01 ETS6 parameters — Input Channel 1:
Enable function: YES
Enable object: Communication object "Enable CH1"
Enable value: 1 (channel active when armed GA = 1)
Disable value: 0 (channel silent when armed GA = 0)
Group address links:
"Enable CH1" object ← GA 8/3/0 (Alarm Armed)
Effect:
Disarmed (GA 8/3/0 = 0):
→ Binary input CH1 enabled = OFF
→ Camera relay triggers ignored (no telegram sent)
Armed (GA 8/3/0 = 1):
→ Binary input CH1 enabled = ON
→ Camera relay trigger → GA 8/0/1 alarm telegram sent
→ Logic module fires full alarm response
Alternative approach (logic AND gate):
Use MDT Logic Module AND gate:
Input A: GA 8/0/1 (camera relay)
Input B: GA 8/3/0 (armed status)
Output: GA 8/0/10 (qualified alarm → horn/DALI)Common cameras with relay output
The following camera models are verified to have usable relay outputs suitable for KNX binary input integration. All provide potential-free dry contacts unless otherwise noted.
Mobotix
- · M73 (1× relay, NO/NC)
- · P71 (2× relay)
- · S74 (1× relay, 24V max)
Relay output under 'MxMessageSystem' in camera web UI — configure 'Relay Output 1 → Motion'
Axis
- · P3245-V (I/O port, 12V max)
- · P1375 (relay, dry contact)
- · Q6135-LE (relay output)
Configure via AXIS Device Manager: Action Rules → Relay → Motion Detection trigger
Hanwha
- · QNV-8080R (alarm output 12V)
- · XNV-8080R (alarm output)
- · QNO-8080R (alarm output)
Alarm output is open-collector 12V — use MDT SCN-8V.01 in 24V mode with pull-up resistor
Maintenance considerations
Relay-based KNX integration is robust but requires periodic verification to confirm the complete alarm chain is operational. Unlike IP-based integrations, a broken relay wire will fail silently — no error message appears on the KNX system.
Periodic test procedure (monthly recommended)
1. Arm the system (GA 8/3/0 = 1) from KNX touchpanel 2. For each camera: a. Wave hand in front of camera (trigger motion) b. Observe ETS6 Group Monitor — GA 8/0/x should pulse to 1 c. Confirm DALI scene activates in affected zone d. Confirm alarm horn sounds (brief pulse — silence manually) e. Confirm ARISTO BewO email received within 60 seconds 3. Test tamper alarm: a. Cover camera lens with hand b. GA 8/1/x should activate (tamper event) 4. Test video loss: a. Disconnect camera network cable briefly b. Some cameras: relay activates on video loss event c. Reconnect — relay should release within 30s 5. Disarm system (GA 8/3/0 = 0) a. Wave hand in front of camera b. Confirm no alarm response fired (binary input disabled) Document results in site maintenance log with date and tester.
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