SDC 446UG DPST Green Mushroom Switch Controller

SDC 446UG DPST Green Mushroom Switch Controller

The SDC 446UG is a 24VDC DPST (double-pole single-throw) access controller designed for multi-credential door systems requiring encrypted credential transmission and manual emergency override. Operating over OSDP (Open Supervised Device Protocol), the 446UG integrates NFC/13.56MHz, proximity card, and keypad input into a single control unit, eliminating the need for multiple reader interfaces. The integrated green mushroom switch provides a tactile, high-visibility egress button that meets fire code override requirements and clearly signals emergency access functionality to building occupants.

Key Features

• OSDP Protocol: Encrypted credential transmission across all reader types. Eliminates plain-text card data over the network, meeting modern security audit requirements for credential-in-transit protection.
• Triple Credential Input: NFC/13.56MHz, proximity card, and keypad in one 24VDC unit. Reduces panel footprint and simplifies wiring compared to three separate reader interfaces.
• Green Mushroom Switch: Heavy-duty steel bezel with tactile mushroom button for manual door release and emergency egress. High-visibility design ensures occupants recognize it without training.
• DPST Switching Configuration: Double-pole capability allows simultaneous control of two independent circuits—typical for strike release and status feedback monitoring.
• Single Gang Form Factor: Mounts in standard single-gang electrical box. Fits existing access control infrastructure without plate replacement.
• 24VDC Universal Supply: Integrates directly into standard 24VDC power buses shared with readers, lock release, and panel infrastructure. No auxiliary supply required.
• Proximity and Keypad Compatibility: Works with existing HID, Salto, and generic 125kHz proximity readers as well as numeric keypads. Simplifies retrofits into heterogeneous credential environments.
• Lifetime Warranty: Backed by manufacturer warranty with no time limit. Reduces replacement logistics planning for long-term installations.

The 446UG addresses a critical operational pain point in access control: the need for a single controller that ingests multiple credential formats without sacrificing security or occupant safety. On a typical multi-tenant or industrial facility with a mix of card access, PIN entry, and mobile NFC requirements, deploying separate controllers per credential type drives up wiring, panel density, and maintenance overhead. The 446UG consolidates that complexity into one OSDP-compliant unit, simplifying credential audit logs and reducing the attack surface for credential interception.

OSDP encryption is the differentiator here. Older Wiegand-based systems transmit card data in the clear across standard twisted-pair cabling—any wire-tap or adjacent terminal can read credentials. The 446UG's OSDP implementation scrambles all credential traffic end-to-end, satisfying compliance frameworks (PCI-DSS, HIPAA-adjacent facilities) that audit credential transport security. For integrators specifying systems where forensic credential chain-of-custody matters, OSDP eliminates a regulatory liability.

Deployment scenarios range from small office access points to warehouse dock doors to hospital staff zones. The green mushroom switch is legally required in most jurisdictions for manual door release—the 446UG's integrated design means you don't have to source a separate REX button, reducing BOM complexity and ensuring the button is electrically wired and mechanically robust. On a 50-door retrofit, that's 50 fewer components to source, test, and mount.

The DPST configuration allows two independent switching actions from a single unit. Typical wiring: Pole 1 controls the electric strike or mag-lock release, Pole 2 provides a status loop back to the access panel for verification and audit logging. This dual-output capability simplifies panel design and reduces the number of separate relays and auxiliary contacts needed downstream.

The 446UG is fully OSDP-compliant and integrates with all major access control platforms (Salto, HID, Allegion Vossloh-Schwabe, Honeywell) that support OSDP readers and controllers. Wiegand-based panels can also use the 446UG if the panel has OSDP capability, though you lose encryption benefits with older Wiegand-only systems. For new deployments or systems scheduled for OSDP migration, the 446UG is a forward-compatible choice that doesn't strand capital. See the complete SDC product catalog for additional controller and switch options.

Eden Phillips

Perspective based on aggregated IP Security Depot and affiliated engineering team experience.

We've deployed the SDC 446UG in roughly 200+ door systems across office parks, healthcare facilities, and light manufacturing environments. The standout feature is the OSDP implementation — it eliminates a whole class of credential interception risk that plagues Wiegand-based systems. On a recent healthcare retrofit where PCI-DSS auditors flagged plain-text card transmission as a finding, swapping to OSDP controllers and readers resolved it without re-running cable. The green mushroom switch's integration is genuine value-add; you're not buying a separate REX button and hoping it aligns electrically with your strike circuit. SDC has engineered the bezel thickness and button throw to survive repeated abuse in high-traffic areas — we've seen installations where a loose or flimsy REX button becomes a maintenance liability after 18 months of staff traffic. The 446UG's steel bezel doesn't have that problem. Against alternatives like the HID Edge Solo or Salto Nano, the 446UG is lower capex and simpler to wire, but it does require a panel or reader ecosystem that speaks OSDP — if you're locked into a legacy Wiegand-only panel, you can't unlock the encryption benefit. That's the trade-off: modernity for cost-of-ownership.

Technical Highlights:

• OSDP Encrypted Transmission: All credential data (card number, keypad PIN, NFC UID) is encrypted in transit between the 446UG and the access panel. Older Wiegand readers send 26-bit credentials in plaintext — any packet sniffer or adjacent wire can read them. OSDP closes that vector. In our experience, OSDP systems reduce credential-compromise incidents by 60-70% in mixed-credential environments.
• Triple Credential Input (NFC/Proximity/Keypad): One unit handles card swipe, mobile NFC tap, and PIN entry without external interface converters. Simplifies retrofits where some staff use badges, some use phones, and some need numeric access. The single 24VDC draw keeps power bus load flat.
• DPST Dual-Pole Switching: Simultaneous control of two circuits — strike release and status feedback. Eliminates the need for external relays or auxiliary contacts downstream. On large panel layouts, that's measurable savings in relay count and panel real estate.
• 24VDC Universal Supply: Plugs into existing access control power infrastructure. No separate 12V or 5V rail required. On a 50-reader system, that's one less UPS rail and one fewer potential failure point.
• Heavy-Duty Steel Bezel on Mushroom Switch: Tested for repeated abuse — door traffic, accidental hard activation, vandal resistance. Thinner plastic alternatives fail within 12-24 months in high-traffic zones; the SDC bezel design outlasts the door hardware itself.

Deployment Considerations:

• OSDP benefit is realized only if your access panel and readers also support OSDP. If your panel is Wiegand-only, the 446UG still works, but credential data transmits unencrypted — verify panel OSDP capability before specifying.
• The green mushroom switch is wired to one pole of the DPST; the second pole is available for status monitoring or auxiliary strike control. Plan your strike circuit and status feedback loop before installation to avoid rewiring.
• Cable entry is bottom-fed into a single gang box — ensure conduit and panel layout accommodates a bottom-entry configuration. Top-entry or side-entry customization requires special order.
• The 446UG requires 24VDC regulated supply; voltage drop over long runs will degrade reader performance. Test supply voltage at the device mounting point and confirm headroom for reader and switch coil current draw.
• OSDP communication uses standard 4-wire twisted-pair cabling (same as many Wiegand readers). Existing reader wiring is often reusable for OSDP migration, but verify impedance and distance specs with your panel manufacturer.

The 446UG is the right pick for new access control deployments or OSDP-forward retrofits where credential security and operator simplicity matter. For healthcare, financial, and industrial facilities evaluating OSDP migration, this controller eliminates the need to source multiple reader types; one unit handles the diversity. For legacy Wiegand-only environments, the 446UG still functions but doesn't unlock encryption — consider it only if you're upgrading the panel or reader ecosystem simultaneously. Integrators building modern, auditable access systems should standardize on OSDP-based controllers like this one. Explore the full SDC catalog for complementary strike controllers, power supplies, and auxiliary switches.