At a Glance. For most machine guarding applications, Schmersal RSS 36 (RFID-coded, PL e / Cat 4) is the best fit when you need a tamper-proof safety door lock with high-level coding; RSS 16 is the cost-effective choice for standard PL d / Cat 4 doors with mechanical coding; AZ 16 remains the proven classic for PL d / Cat 1 or Cat 4 (with separate monitoring) electromechanical door switches; and SLC 440 safety light curtains are used when a non-contact, finger/hand protection zone is needed at the machine access point. This guide walks through the four families side by side and gives a practical decision flow.
1. Side-by-Side Comparison Table
| Feature | RSS 36 (RFID) | RSS 16 (RFID) | AZ 16 (Electro-mech.) | SLC 440 (Light Curtain) |
|---|---|---|---|---|
| Coding | RFID, individually coded (high) | RFID, standard / unique (med) | Mechanical, key-actuated | Optical, no coding required |
| PL / Cat (EN ISO 13849) | PL e / Cat 4 | PL d / Cat 4 | PL d / Cat 1 (or Cat 4 with 2 ch.) | PL e / Cat 4 (type 4) |
| Locking force (Fzh) | 1,500 N or 2,500 N | 1,500 N | up to 2,000 N (with latch) | N/A (non-contact) |
| IP rating | IP65 / IP67 | IP65 / IP67 | IP67 | IP65 |
| Connection | M12, 5 / 8 pole | M12, 5 / 8 pole | Cable entry or M12 | M12, 4 / 5 pole |
| Typical use | Tamper-proof guard doors, process protection | Standard guard doors with diagnostics | Classic hinged / sliding guard doors | Finger / hand protection at machine openings |
| Series actuator required | Yes (matched RSS 36 actuator) | Yes (matched RSS 16 actuator) | Yes (AZ 16 actuator key) | No — transmitter + receiver pair |
| Approx. price band (EUR) | €€€ (premium) | €€ | € | €€€€ (length-dependent) |
| Stock examples | Custom order | RSS16-I2-D-R-SK | Custom order | SLC440COM-R-0810-14 |
2. Decision Guide — Which Schmersal Series Fits Your Application?
- Need tamper-proof, high-coded lockout? → RSS 36 (RFID individually coded, defeats bypass attempts).
- Standard guard door, want RFID diagnostics at fair cost? → RSS 16 (e.g. RSS16-I2-D-R-SK).
- Legacy / replacement of older AZ 16, mechanical key OK? → AZ 16 (simple, robust, lowest cost).
- Need non-contact finger/hand protection at an opening? → SLC 440 safety light curtain (SLC440COM-R-0810-14, SLC440COM-E-0730-30).
- Need both — light curtain at access + locking at hinged door? → Combine SLC 440 + RSS 36 with a common safety relay (e.g. Schmersal SRB-E or ESS21S1 safety timer).
- Position monitoring of a hinged guard? → ZS 235 (ZS 235-11Z-ST) or T5C 236 (T5C 236-02Z-M20) limit switch style.
- Hazardous area, need Ex-rated switch? → TS 336 (TS 336-02Z-M20) ATEX/IECEx position switch.
3. Safety Light Curtain vs Door Lock — How to Choose
Light curtains (SLC 440) and door locks (RSS / AZ) solve different problems:
- Light curtain: detects a person breaking an optical beam at the opening. Used when the operator must frequently reach into a machine (e.g. feeding parts), and physical guarding is impractical.
- Door lock with monitoring: detects whether a guard door is closed and locked. Used when the machine must not start (or must stop) while the guard is open, often combined with a time-delay for run-down.
- Many machines use both: a light curtain for visibility / ease of access, plus a locked guard door for full-body access during maintenance.
4. Safety Relay Pairing (one line of guidance)
The safety switch / light curtain must be wired to a safety relay or safety controller that meets the same PL / Cat level. Schmersal's own SRB-E series and the ESS21S1/EKM150 safety timer are common pairings. When in doubt, the safety evaluation (SISTEMA / PAScal) must cover the combined subsystem, not just the switch.
5. Quick FAQ
Q: Is RSS 36 backward-compatible with RSS 16 actuators?
No. They use different RFID protocols and mechanical geometries. Always pair RSS 36 with RSS 36 actuators.
Q: Can I cascade two SLC 440 curtains?
Yes, with Schmersal safety relays that support cascade input; check the manual for the specific receiver firmware.
Q: Do I need ATEX for an outdoor cabinet?
Not necessarily — ATEX is for explosive atmospheres. Outdoor enclosures usually just need a higher IP (IP67 / IP69K) — RSS 36 in IP67 is a typical outdoor pick.
6. Related Products in Stock
- Schmersal RSS16-I2-D-R-SK — RFID-coded safety door switch, PL d / Cat 4.
- Schmersal SLC440COM-R-0810-14 — Type 4 safety light curtain, receiver, 810 mm protected height.
- Schmersal SLC440COM-E-0730-30 — Type 4 safety light curtain, 730 mm, 30 mm resolution.
- Schmersal ZS 235-11Z-ST — Snap-action limit switch for guard-door position.
- Schmersal T5C 236-02Z-M20 — Tongue-operated safety switch, classic AZ family.
- Schmersal TS 336-02Z-M20 — ATEX/IECEx position switch for hazardous areas.
- Schmersal ESS21S1/EKM150 — Safety timer / control module.
- Schmersal VWS21.1 — Command and signalling device.
Need help picking the right Schmersal safety switch or light curtain for your machine guarding application? Request a quote with your PL / Cat target and our engineers will cross-reference the matching actuator, safety relay and connector — all from stock at Glorient.