## Common ground
All options are types of motion or pressure sensors used for detection, measurement, or triggering actions.
## Options at a glance
**8526.92 – Radio signal transmission**
- **Defining trait:** Sends a wireless radio signal upon detecting movement.
- **Typical examples:** Wireless security sensor sending alert to central hub via radio.
- **Best fit when:** The sensor communicates wirelessly without direct connection to another device.
**8531.10 – Alarm activation via sound/visual signal**
- **Defining trait:** Directly triggers an audible or visual alarm upon detection.
- **Typical examples:** PIR sensor with built-in siren; pressure mat that flashes light when stepped on.
- **Best fit when:** The device itself produces an alarm, not just sends a signal.
**8531.80 – Signal to external device (e.g. phone, alarm)**
- **Defining trait:** Sends detection signal to another system (e.g., home alarm or smartphone).
- **Typical examples:** Door sensor sending alert to app; window sensor triggering home security system.
- **Best fit when:** The sensor acts as part of a networked system, not standalone alarm.
**8531.90 – Part of an alarm system**
- **Defining trait:** Designed specifically to be integrated into a larger alarm setup.
- **Typical examples:** Hardwired PIR sensor in a commercial security panel.
- **Best fit when:** The sensor is not standalone and only functions within a defined alarm network.
**8536.50 – Switch-type for automation (lights, doors)**
- **Defining trait:** Used to automatically turn on/off devices like lights or doors.
- **Typical examples:** Motion-activated hallway light; automatic door opener.
- **Best fit when:** Purpose is environmental control, not security or measurement.
**8543.70 – Specialized individual functions**
- **Defining trait:** Unique function beyond basic detection (e.g., asset tracking, access control).
- **Typical examples:** Wireless sensor for tracking equipment; door status monitor with temp sensing.
- **Best fit when:** Sensor has a niche or multi-purpose role not covered by others.
**9031.49 – Optical sensors for measurement/testing/control**
- **Defining trait:** Uses optical technology for precise measurement, testing, or process control.
- **Typical examples:** Laser displacement sensor; optical encoder in machinery.
- **Best fit when:** Used in industrial, lab, or precision environments.
**9031.80 – Other sensors for measurement/testing/control**
- **Defining trait:** Non-optical sensors used for measurement, testing, or control.
- **Typical examples:** Pressure sensor in medical device; motion sensor in factory automation.
- **Best fit when:** General-purpose sensing in technical or industrial settings.
## Key differences
| Option | Primary Function | Communication | Integration Level | Use Case Type |
|-------|------------------|---------------|--------------------|----------------|
| 8526.92 | Wireless alert | Radio signal | Low | Security alert |
| 8531.10 | Direct alarm | None (built-in) | Low | Immediate warning |
| 8531.80 | Signal to device | Wired/wireless | Medium | Networked system |
| 8531.90 | Part of alarm | Hardwired | High | Integrated security |
| 8536.50 | Automation trigger | None | Low | Smart home/industrial control |
| 8543.70 | Specialized function | Varies | Varies | Niche applications |
| 9031.49 | Measurement/control | Varies | Medium | Industrial/lab use |
| 9031.80 | Measurement/control | Varies | Medium | General technical use |
## How to choose
- Does it trigger a sound or light directly? → 8531.10
- Does it send a signal to a phone, alarm, or network? → 8531.80
- Is it used for automatic lighting or door control? → 8536.50
- Is it part of a larger alarm system (e.g., hardwired)? → 8531.90
- Is it used for precise measurement/testing/control? → 9031.49 or 9031.80
- Does it have a unique function (e.g., asset tracking)? → 8543.70
## Overlaps & pitfalls
- **Overlaps:** A sensor that sends a signal to an alarm system (8531.80) may also be part of an alarm system (8531.90).
- **Pitfall:** "Alarm" in 8531.10 and 8531.90 can mislead—only 8531.10 has built-in alarm; 8531.90 is integrated.
- **Priority rule:** If the sensor’s main purpose is *alarm triggering*, use 8531.10 or 8531.90. If it’s *measurement/control*, use 9031.x. Choose based on primary function