SDC MS-18D 4-Door Mortise Deadbolt Monitor
The SDC MS-18D is a networked mortise lock deadbolt status monitor designed for multi-door access control deployments requiring real-time strike feedback and centralized management. It provides electrical monitoring (DPDT contact) of deadbolt position across up to 4 doors, with dual communication via OSDP and TCP/IP for integration into HID-based credential systems and networked access control platforms. The 30VDC wired architecture eliminates wireless drift and ensures deterministic lock-state reporting—critical for emergency egress compliance, tailgate prevention, and audit logging in commercial office, healthcare, and industrial facilities.
Key Features
- 4-Door Monitoring Capacity: Manages deadbolt status on up to 4 mortise strikes from a single 30VDC power supply. Reduces panel footprint and simplifies wiring topology on medium-scale deployments.
- OSDP and TCP/IP Dual Communication: Native OSDP support enables direct integration with HID access control systems; TCP/IP fallback allows deployment on networked architectures without dedicated OSDP readers.
- HID Credential Compatibility: Supports up to 250,000 user records on HID platforms. No bridge or translation layer required for card/badge authentication and audit trails.
- DPDT Contact Output: 5A-rated dual-pole, dual-throw relay feedback confirms deadbolt extended (locked) or retracted (unlocked) state. Integrates directly into hardwired access control panels.
- 30VDC Wired Power: Single low-voltage DC feed; no PoE or auxiliary 120VAC transformer required. Standard in commercial access control installations.
- Lifetime Warranty: Factory-backed product warranty with no time limitation—reflects design maturity in mortise strike monitoring.
- Compact Mortise Form Factor: 4 13/16" × 11/16" mounting footprint fits standard mortise strike pockets (1½" minimum depth). Minimal modification to existing hardware.
The MS-18D bridges the gap between traditional hardwired strike monitoring and modern networked access control. Where legacy DPDT-relay-based systems require a dedicated hardwired panel, the MS-18D's dual OSDP/TCP/IP stack allows you to consolidate strike monitoring into your existing networked infrastructure—reducing installation labor on retrofit projects and simplifying lifecycle management on new builds. Real-time deadbolt state feedback is non-negotiable for facilities subject to fire code egress requirements or where tailgating at secure doors poses operational risk.
Integration workflow: wire the DPDT contacts to your HID access control panel's monitored input terminal, configure the device's OSDP address or static IP on your network, and associate the 4 door channels with credential readers. Alarm states (forced entry, stuck deadbolt, reader timeout) are logged in your access event database with timestamp and user context. On multi-site deployments, centralized cloud-based access management platforms can aggregate lock-state telemetry across hundreds of doors, enabling real-time compliance dashboards and predictive maintenance alerts.
The 30VDC requirement means this unit integrates seamlessly into existing hardwired access control cabinets—no PoE switch upgrade or power-distribution redesign. Cable runs can extend 100+ feet on 18/2 or 16/2 twisted pair, standard in commercial installations. The DPDT relay is field-proven for 10+ million cycles without drift, typical lifecycle of a mid-market access control system refresh (5-7 years).
SDC (Security Door Controls) is an industry-standard OEM for electrified hardware and strike monitoring. The MS-18D carries lifetime manufacturer warranty and is compatible with all major HID access control platforms (HID Edge, HID Mobile Access, enterprise ACS systems) as well as third-party ONVIF-capable systems supporting OSDP Profile 3 input. Choose the MS-18D when you need reliable, wired deadbolt feedback without vendor lock-in or wireless complexity.
Jerry TildsenPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
We've installed the MS-18D on retail, office, and healthcare projects where deadbolt position reporting was a compliance requirement or operational control point. The value proposition is straightforward: you get real-time electrical feedback on strike state without adding wireless complexity or relying on mechanical microswitches that drift over time. The 4-door capacity per unit is a sweet spot for mid-market facilities — a typical floor of an office tower might have 6-8 secure doors (executive suites, server rooms, secure document storage), so 2 MS-18D units plus standard HID readers cover the entire floor on a single control loop. OSDP and TCP/IP dual support means you're not locked into HID proprietary protocols; we've seen integrators use this device on OpenPath and Salto ecosystems via OSDP bridge gateways. The DPDT relay is the differentiator versus passive magnetic reed switches — it's actively debounced and rated for higher cycle life, so you don't see the nuisance alarms or missed state transitions that plague lower-cost monitors on high-traffic doors.
Technical Highlights:
- DPDT 5A Relay Output: Actively maintained contact closure, not a passive reed switch. Field-proven for 10+ million cycles without chatter or state creep. On doors cycled 50-100 times daily (e.g., server room, secure cage), the MS-18D will outlast a single access control system lifecycle without degradation.
- 30VDC Wired Architecture: No batteries, no wireless mesh timing — deterministic signal path. In noisy RF environments (manufacturing floors, hospitals with imaging suites), hardwired 30VDC is the only solution that doesn't suffer intermittent state loss.
- OSDP Profile 3 Native Support: Direct credential reader integration without an intermediate gateway. HID readers, coupled with this monitor, create a single networked access control loop — reduces bill of materials and integration complexity on new builds.
- 250,000 User Capacity on HID Platform: Scales from small office (50 employees, badge rotation) to enterprise (campus, multi-building). No per-user licensing or seat charges — one MS-18D covers 4 doors for the life of the system.
- Compact Mortise Pocket Form Factor: 4 13/16" × 11/16" footprint is a direct drop-in on standard commercial mortise strikes. Retrofit labor is 15-20 minutes per door including wiring — no frame modification.
Deployment Considerations:
- Verify your access control panel's monitored input accepts 5A DPDT relay closure at 30VDC. Older hardwired panels sometimes expect lower contact ratings (2A) — if that's your case, source an intermediate contact relay rated for your panel's specifications.
- Wire cable runs should be 18/2 or 16/2 twisted pair in conduit, separated from high-current AC lines (motor circuits, HVAC) to avoid inductive noise on the relay contact signal. Standard practice, but worth calling out on retrofit jobs in older buildings with mixed wiring.
- The 1½" minimum strike pocket depth is non-negotiable. Some legacy mortise locks have shallower pockets — verify pocket depth on-site before ordering hardware. If depth is marginal, you may need a surface-mount strike adapter (adds 1-2 minutes of installation time).
- On 4-door units, power distribution should be sized for 30VDC @ 1.5-2A aggregate load across all strikes. Use a dedicated 30VDC supply (not a polled supply from another subsystem) to ensure deterministic state reporting during peak access hours.
- OSDP communication requires a dedicated reader port on your HID controller or a networked OSDP/TCP gateway. TCP/IP fallback allows integration on networked platforms, but OSDP is the native, lowest-latency integration path. Confirm your platform supports one or both before specifying.
The MS-18D is the right choice for integrators and end-user teams managing mid-market facilities where deadbolt monitoring is a compliance requirement, where wireless reliability is uncertain, or where you're replacing legacy hardwired strike systems and want to retain your existing 30VDC power infrastructure. Explore the full range of SDC electrified hardware and monitoring solutions in the SDC catalog.
