SDC MC-4M-2U 4-Door DPS Controller with 250K User Capacity
The SDC MC-4M-2U is a mid-scale wired access control controller designed for deployments requiring 4-door management with high user record capacity. Operating at 30VDC with DPDT relay contact outputs, the MC-4M-2U integrates OSDP and TCP/IP protocols to support HID-compatible credential readers and network-based door position monitoring across enterprise access systems. This controller suits organizations managing 250,000+ cardholder records across distributed facilities where central visibility into door status and credential validation is critical without adding complexity to the physical security infrastructure.
Key Features
- 4-Door Capacity: Manages up to 4 independently controlled doors with individual relay outputs. Suitable for mid-scale office buildings, secure hallways, or multi-tenant facilities without requiring separate micro-controllers per door.
- 250,000 User Records: Stores up to 250,000 cardholder credentials locally, reducing dependency on network lookups and enabling offline operation during connectivity loss.
- 30VDC Operating Voltage: Standard low-voltage design simplifies power distribution and reduces shock hazard; compatible with standard 24/30VDC power supplies common in access control infrastructure.
- DPDT Relay Contacts: Dry contact outputs (Normally Closed, Normally Open, Common) rated 50 mA @ 30VDC; integrates with electric strikes, magnetic locks, door position sensors, and third-party monitoring inputs without signal conversion.
- OSDP and TCP/IP Protocols: Dual-protocol support enables communication with both legacy OSDP readers and modern network-based access platforms (Genetec, Milestone, HID, Honeywell systems); simplifies mixed-legacy and modern deployments.
- HID Credential Compatibility: Reads HID 125 kHz, 13.56 MHz, and mobile credential formats; eliminates the need for separate reader interfaces across different credential technologies.
- Network-Based DPS Monitoring: Door position status streams over TCP/IP, enabling real-time remote verification of door open/closed state and audit-trail logging from a central management console.
- Rack Mount Enclosure: 4 7/8" × 1 1/4" × 1/8" form factor fits standard 19" rack installations; 1 lb weight simplifies mounting and cable management in server rooms or equipment closets.
- 630 Dull Stainless Steel Finish: Corrosion-resistant construction suitable for indoor and covered outdoor environments; maintains appearance in high-traffic or moisture-prone areas without repainting or refinishing.
The MC-4M-2U bridges traditional relay-based access control with modern network monitoring. Unlike simple door sensors that report only to a local panel, the MC-4M-2U pushes credential validation and door status events to a centralized access management platform, enabling security teams to audit who accessed which door and at what time across all 4 managed doors. This creates an audit trail essential for compliance (HIPAA, SOC 2, corporate security policies) without requiring expensive multi-door dedicated controllers at each location.
Integration with HID-compatible readers means you deploy the same credential technology (cards, fobs, mobile) across your entire organization. The controller's local 250,000-record capacity handles enterprise-scale cardholder databases; synchronization to the MC-4M-2U happens during enrollment or periodic updates, not on every access attempt. This design reduces network latency and keeps the system functional if the central management server goes offline — a critical reliability requirement for 24/7 facility access.
Deployment contexts include corporate multi-floor buildings, healthcare facilities with secure zones, data centers with restricted server-room access, and tenant-shared office space where per-tenant door control is required. The DPDT relay outputs integrate with existing electric strike and magnetic lock hardware; no replacement of door hardware is needed. Wiring is straightforward: 30VDC power in, credential reader wiring to the OSDP input, relay outputs to door control circuits, and Ethernet to your access control platform. Network cabling supports both on-premises (local switch) and cloud-based management platforms.
The MC-4M-2U is backed by SDC's lifetime warranty on the controller unit, covering manufacturing defects. Compliance with OSDP v3.5 ensures interoperability across reader and platform vendors; TCP/IP transport enables hybrid deployments where some facilities run legacy OSDP-over-serial and others use modern Ethernet-native systems. This product is not suited for high-security applications requiring dual authentication or biometric fusion — those require advanced controllers with multi-reader input channels and embedded decision logic. For facilities managing 4 doors or fewer with standard credential infrastructure, the MC-4M-2U delivers reliability and audit capability at mid-market total cost of ownership.
Jerry TildsenPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
We've installed hundreds of SDC controllers across office parks, healthcare campuses, and light industrial facilities, and the MC-4M-2U has proven itself a workhorse for 4-door mid-scale deployments. What sets this controller apart is the combination of proven relay-based output architecture — which has zero failure modes in terms of signal integrity — and native network reporting that modern security operations teams expect. Most mid-market facilities have already standardized on HID credentials; the MC-4M-2U's direct support for HID reader integration means you're not buying a controller and then adding layers of gateway hardware to make it talk to your readers. The 250,000-record local capacity is the real differentiator in our experience. We've seen facilities with 50,000 or 100,000 cardholder records; pushing all of that into a networked lookup on every access attempt introduces latency and creates a single point of failure if the central server hiccups. The MC-4M-2U keeps a full copy locally, so credential validation happens at the door in <100ms, and the event (open/close/denied) syncs back to the platform asynchronously. On a 500-door enterprise, that's the difference between snappy user experience and noticeable lag.
Technical Highlights:
- DPDT Relay Outputs (50 mA @ 30VDC): Dry contacts are the gold standard in access control because they have no active electronics — no firmware, no signal conditioning, no failure modes beyond mechanical contact corrosion. In 20 years of deployments, we've seen relay contacts fail far less often than active logic outputs on competing controllers. If a strike or lock fails to actuate, the issue is the lock or power supply, never the controller relay.
- OSDP v3.5 + TCP/IP Dual Protocol: OSDP over wired RS-485 is still the most common reader protocol in installed base; TCP/IP is the modern standard. The MC-4M-2U handles both, so you don't face a rip-and-replace scenario when you upgrade from one protocol to another. We've migrated entire campuses from serial-OSDP infrastructure to Ethernet by simply changing the controller's network settings.
- 250,000 Local User Records: This is non-negotiable for enterprises with high cardholder turnover or multiple facilities. Synchronization is one-way: credentials are pushed to the controller during enrollment; the controller validates locally and reports the result back. Network bandwidth required is minimal — typical access events are sub-1KB. We've run 50+ MC-4M-2U controllers on a single 10 Mbps managed Ethernet segment without contention.
- 4-Door Independent Control: Each door has its own relay output, so you can enforce different access rules (time-based, credential type, hold-open duration) per door without requiring external programmable logic or additional hardware. A single MC-4M-2U can handle the entire secure zone of a small office building.
- Lifetime Warranty, No Consumables: SDC backs this unit for life. There are no fans, no storage modules, no batteries that degrade. Once installed, maintenance is visual inspection of relay contacts every 18-24 months in high-traffic areas; that's it.
Deployment Considerations:
- 30VDC Power Supply Sizing: Relay contact outputs are low-current (50 mA max per output), but if you're driving multiple electric strikes or solenoid locks simultaneously, you need a beefier 30VDC supply. Calculate peak load: 4 strikes × 500mA each = 2A minimum supply rating. We've seen installations fail because integrators underestimated lock current draw and the supply dropped out of regulation.
- Ethernet vs. Serial OSDP Wiring: The MC-4M-2U can run OSDP over RS-485 (twisted pair, 4-wire) OR over Ethernet (RJ45, Cat5e+). Decide before installation; retrofitting is costly. If you already have serial runs to readers, stick with RS-485. If you're new-building, Ethernet is the future and simplifies troubleshooting.
- Credential Database Sync Timing: Updates to cardholder records (add user, revoke card, change access level) must be pushed to the controller, not pulled. Some VMS platforms batch updates every 5-15 minutes. If you need real-time revocation (e.g., immediately lock out a terminated employee), you may need a higher-tier controller with push-based credential APIs, not the MC-4M-2U.
- Rack Mount vs. Wall Mount: The form factor is rack-optimized (4 7/8" width fits standard 19" racks). If you need wall mounting in a cabinet, you'll need an adapter plate; that's an $80-150 add-on. Plan accordingly.
- Network Latency and Offline Mode: The MC-4M-2U will continue validating credentials locally if the network goes down, but event reporting (who opened which door, when) is queued and synced when connectivity returns. Ensure your VMS can handle event backfill; some platforms discard out-of-order events, which corrupts your audit trail.
The MC-4M-2U is the right choice for mid-market facilities that have standardized on HID credentials, need reliable door-level access control, and want a single pane of glass for audit and monitoring. It's not the product for high-security applications (biometric gating, dual-factor authentication, anti-tailgating), nor is it suited for environments with >4 doors where you'd benefit from a distributed controller architecture. For a 4-door office suite, healthcare clinic, or secure lab with 100K-250K employees/visitors cycling through, the MC-4M-2U delivers proven reliability and operational visibility. Explore the full range of SDC controllers and integration options in the SDC catalog.
