Omron D4BS-4AFS Safety Door Switch
Omron D4BS-4AFS is a 1-conduit safety door switch with an M20 connection for monitoring protective doors and movable machine guards. A Type 2 low-level coded interlock provides mechanical guard-position detection, while the direct opening mechanism supports positive contact separation when the protective door is operated. The switch supports operating speeds from 0.1 to 0.5 m/s and provides 19.61 N minimum direct opening force with 20 mm minimum travel. IP67 enclosure protection supports demanding industrial machine installations. The D4BS-4AFS belongs to the D4BS series within the industrial safety door switch range from Omron machine safety products, supporting guard detection and machine access monitoring.

| Brand | Omron |
| Product Type | Safety Door Switch |
| Model Number | D4BS-4AFS |
Omron D4BS-4AFS Safety Door Switch - Technical Specifications
| Specification | Value |
|---|---|
| Type | 1-conduit type |
| Conduit outlet/Connector | M20 |
| Interlock type | Type 2 |
| Coding level | Low level coded |
| Degree of protection | IP67 |
| Operating speed | 0.1 m/s to 0.5 m/s |
| Direct opening force | 19.61 N min |
| Direct opening travel | 20 mm min |
| Contact resistance | 25 mΩ max. |
| Rated insulation voltage (Ui) | 600 V |
| Rated frequency | 50/60 Hz |
| Insulation resistance | 100 MΩ min. |
| Contact gap | 2 × 2 mm min |
| Vibration resistance | Malfunction 10 to 55 Hz, 0.65 mm single amplitude |
| Shock resistance | Destruction: 1,000 m/s2 min. Malfunction: 300 m/s2 min |
| Ambient operating temperature | −40 to 80°C |
| Ambient operating humidity | 95% max |
| Weight | Approx. 285 g |
The Omron D4BS-4AFS Safety Door Switch uses a 1-conduit construction with an M20 connection for protective-door and machine guard monitoring. A Type 2 low-level coded interlock provides mechanical guard-position detection, while IP67 enclosure protection supports industrial machine installations. Its direct opening mechanism provides 19.61 N minimum force with 20 mm minimum travel, supporting positive mechanical contact separation when the protective guard is operated. The switch supports guard movement from 0.1 to 0.5 m/s.
The main selection relationships for this model are its D4BS series, 1-conduit construction, M20 cable entry, Type 2 interlock and direct opening operation. Together, these attributes connect the D4BS-4AFS with safety door switches, machine guard detection, protective access monitoring and industrial safety circuits. The M20 connection is particularly useful for distinguishing this configuration from D4BS variants supplied with alternative conduit formats. When the protective door is opened, the direct opening mechanism provides mechanical contact separation as part of the guard-monitoring function. This makes the model relevant to machinery where access doors or movable guards need position detection as part of the machine safety design. For another D4BS safety door switch using an M20 1-conduit arrangement and the same primary direct-opening characteristics, the D4BS-45FS provides a closely related model within the same product family.


