At a Glance. The Schmersal AZM161 solenoid interlock and the Schmersal RSS260 RFID safety sensor both monitor a removable guard — but they protect it differently. The AZM161 is an electromechanical device with real guard locking: a 30 N latching force physically holds the door shut while hazardous motion runs down, then releases it. The RSS260 is a non-contact, individually-coded RFID sensor that detects the guard position with no mechanical wear and with the highest manipulation resistance. The rule: door must stay locked during motion → AZM161; position monitoring with high tamper resistance and washdown tolerance → RSS260.
1. Head-to-Head Specification Table
| Specification | AZM161 (solenoid interlock) | RSS260 (RFID sensor) |
|---|---|---|
| Working principle | Electromechanical, actuator key | RFID, individually coded tag |
| Guard locking | Yes — 30 N latching, power-to-lock | No (position detection only) |
| ISO 14119 coding level | Low | High (individual coding, multi-teach) |
| Standards | EN IEC 61508 | EN IEC 60947-5-3 |
| Certificates | cULus, ASi-SaW | TÜV, cULus, FCC, IC, ANATEL |
| SIL / PL / Category | SIL 1 / PL c / Cat. 3 | Per application (fail-safe OSSD) |
| Outputs | AS-i safety slave (26.5–31.6 VDC) | 2 fail-safe outputs, series-wiring |
| Connection | M12, 4-pole | M8, 8-pole (M12 variants available) |
| Housing / IP | Glass-fibre thermoplastic, IP67 | Thermoplastic, IP67 |
| Ambient temperature | −25…+60 °C | −28…+65 °C |
| Mission time | 20 years | 20 years |
| Mechanical lifetime | 1,000,000 operations | Non-contact (no mechanical wear) |
| Stock pages | AZM161-B-ST1-AS-RAT / AZM161SK-12/12RITU | RSS260-I2-D-F1-ST / RSS260-D-F0-LSTM12 |
2. The Deciding Factor: Locking vs Detection
This is the one question that splits the two families. The AZM161 is a guard-locking device: when the safety circuit commands "lock", a solenoid physically holds the actuator key with 30 N of latching force, and the door simply cannot be opened until the dangerous movement has stopped (power-to-lock, with manual release for emergency exits). That is a functional safety requirement, not a convenience — machines with long rundown times (presses, mixers, centrifuges, high-inertia drives) cannot use a plain sensor because an operator could open the guard while the rotor is still turning.
The RSS260 does the opposite job: it answers "is the guard closed?" with a coded RFID signal, at category-3 level, but it does not physically hold the door. It shines where you need tamper-proof position detection — because each tag is individually coded, a screwdriver, magnet or second tag cannot fool it (ISO 14119 coding level "High", versus the AZM161's "Low" mechanical key).
3. Secondary Selection Criteria
- Alignment tolerance: the RSS260 RFID head tolerates generous offset and off-axis mounting with only ~2 mm hysteresis; the mechanical AZM161 needs a straighter actuator path (actuating play about 5.5 mm) and is more sensitive to door sag.
- Washdown / hygiene: the fully encapsulated RSS260 has no key slot to collect debris and is the better choice for food, pharma and wet processes; the AZM161 has a mechanical slot that should be kept clean.
- Wiring density: RSS260 outputs support series-wiring with cross-circuit detection, so multiple doors chain onto one safety input; the AS-i variant of the AZM161 (26.5–31.6 VDC) also collapses wiring onto a 2-wire bus with integral diagnostics.
- Switching frequency: the AZM161 is rated to 1,000 Hz switching; the RFID read is inherently slower but wear-free over millions of cycles.
4. Selection Summary
| Your requirement | Recommended device |
|---|---|
| Door must remain locked during hazardous motion | AZM161 |
| High-integrity guard position monitoring, no locking needed | RSS260 |
| Washdown / hygiene environment | RSS260 (encapsulated, no slot) |
| Multiple doors on one safety input | RSS260 series-wiring |
| Two-wire AS-i installation, locking required | AZM161 AS-i variant |
5. Replacement and Cross-Reference
Typical replacement patterns:
- Legacy solenoid interlocks (older tongue-operated switches): the AZM161 is the modern drop-in with the same function plus integral diagnostics — match the actuator (ordered separately) and lock/unlock voltage before ordering.
- Legacy coded switches / reed interlocks being upgraded for manipulation resistance: the RSS260 replaces them with individually-coded RFID — confirm the coding level and output interface (OSSD vs AS-i) your controller expects.
Send Glorient the old switch model, the guard type and whether locking is required, and we will return the closest in-stock Schmersal equivalent within one business day.
6. FAQ
Can the RSS260 replace an AZM161 if I need locking?
No. The RSS260 is a non-contact position sensor and provides no locking force. If the safety concept requires the guard to stay closed during rundown, you need a locking device such as the AZM161. Use the RSS260 where detection — not locking — is the function.
What does "power-to-lock" mean on the AZM161?
The solenoid is energised to lock the guard, and releases (with manual release option) when de-energised or on emergency exit. Confirm the required lock/unlock behaviour against your risk assessment, as power-to-unlock variants behave differently.
Why is the RSS260 more resistant to tampering?
Each actuator is individually coded during a multi-teach procedure, and the sensor only responds to its programmed tag. A magnet, a spare key or a second RSS260 tag cannot satisfy it — the reason it is rated ISO 14119 coding level High versus the mechanical Low of the AZM161.
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