SDC 400U-RMB vs SDC MC-4PAK: Specification Comparison
Both the SDC 400U-RMB and SDC MC-4PAK are wired, 4-door networked access controllers from SDC Security Door Controls, targeting commercial and enterprise access control deployments. Each supports up to 250,000 HID credentials locally, communicates via OSDP and TCP/IP, and carries a lifetime warranty. This comparison evaluates the three most decision-relevant dimensions for 4-door controllers: power and electrical requirements, installation and physical form factor, and integration and credential management capabilities.
In This Guide
- How do the power and electrical requirements differ between the 400U-RMB and MC-4PAK?
- What physical and installation differences should installers consider?
- How do the two controllers compare for credential management, protocol support, and system integration?
- Which should you choose: the 400U-RMB or the MC-4PAK?
- Side-by-Side Specs
- FAQ
How do the power and electrical requirements differ between the 400U-RMB and MC-4PAK?
The 400U-RMB operates at 24VDC input voltage, a supply rail that is standard across a wide range of existing access control panel ecosystems and commonly available from off-the-shelf power supplies and UPS devices.
The MC-4PAK requires 30VDC input voltage, which is a less common supply rail in typical access control installations. Installers specifying this unit must verify that the power supply chain supports 30VDC or budget for a dedicated supply. Neither unit's spec sheet states current draw or wattage, so load calculations cannot be completed from provided data alone.
The 6VDC differential is a real installation planning factor: a site standardized on 24VDC panels can drop in the 400U-RMB without adding a new power supply, while the MC-4PAK will require a separate 30VDC-rated source in those environments.
What physical and installation differences should installers consider?
The 400U-RMB lists dimensions of 2½" x 4½" and a weight of 1 lb. Notably, the spec data also lists a secondary voltage of 12VDC and describes a built-in buzzer on a 1-gang wall plate form factor, suggesting this unit is designed for direct wall-plate or surface mounting alongside a reader in a 1-gang box footprint.
The MC-4PAK dimensions are listed as ¾" Diameter and weight of 1 lb. The ¾" diameter figure is anomalous for a 4-door controller and is inconsistent with a panel-style device; it may reflect a data entry error or a sub-component measurement in the available spec record. The MC-4PAK color is specified as White. Package contents are listed only as 'MC-4PAK Controller Unit' with no mention of additional hardware.
The 400U-RMB's buzzer integration eliminates a separate annunciator device in single-reader-per-door deployments. The MC-4PAK has no built-in buzzer specified. The MC-4PAK dimensional data as provided is insufficient to plan enclosure or rough-in requirements; installers should consult the referenced datasheet (/content/product-datasheets/MC-4PAK.pdf) before ordering.
How do the two controllers compare for credential management, protocol support, and system integration?
Both controllers store up to 250,000 HID-compatible credentials locally. This on-board database size is suitable for large enterprise campuses and reduces reliance on continuous connectivity to a central authentication server for door decisions.
Both units support OSDP (Open Supervised Device Protocol) for encrypted, bi-directional reader communication, and TCP/IP for LAN-based management and upstream integration with access control software. Neither spec sheet lists supported access control software platforms by name, so VMS or ACS compatibility must be confirmed with SDC directly.
The 400U-RMB's Cable Category is listed as 'Door Prop Alarms & Annunciators,' implying tighter integration with alarm annunciation subsystems. The MC-4PAK's Cable Category is listed as 'Accessories,' which provides no additional integration signal from the available data. Both units carry a lifetime warranty, equalizing long-term support risk.
Which should you choose: the 400U-RMB or the MC-4PAK?
Our take: The 400U-RMB is the stronger choice when the installation site is standardized on 24VDC power infrastructure and requires an integrated door buzzer annunciator. The most concrete spec delta is input voltage: 400U-RMB at 24VDC versus MC-4PAK at 30VDC, directly affecting power supply compatibility and installation cost. Second, the 400U-RMB includes a built-in buzzer on a 1-gang wall plate; the MC-4PAK lists no equivalent, requiring a separate annunciator device if audible feedback is needed. Third, the 400U-RMB's 2½" x 4½" panel dimensions are consistent with standard access control enclosures, while the MC-4PAK's listed ¾" diameter is dimensionally inconsistent with a 4-door controller and should be verified against the manufacturer datasheet before specifying. Both units are otherwise equivalent on credential capacity (250,000), protocol support (OSDP, TCP/IP), door count (4), and warranty (lifetime). Specify the MC-4PAK only after confirming 30VDC supply availability and resolving the dimensional data discrepancy.
Side-by-Side Comparison
Spec-for-spec, from manufacturer data.
| Specification | SDC 400U-RMB | SDC MC-4PAK |
|---|---|---|
| Product Type | Controller | Controller |
| Door Capacity | 4 doors | 4 doors |
| Input Voltage | 24VDC | 30VDC |
| Max User / Credential Records | 250,000 | 250,000 |
| Credential Format | HID compatible | HID compatible |
| Communication Protocols | OSDP, TCP/IP | OSDP, TCP/IP |
| Connectivity | Wired | Wired |
| Built-in Buzzer | Yes (1-gang wall plate) | — |
| Color | — | White |
| Dimensions | 2½" x 4½" | ¾" Diameter (unverified — check datasheet) |
| Weight | 1 lb | 1 lb |
| Warranty | Lifetime | Lifetime |
| Package Contents | — | MC-4PAK Controller Unit |
| Cable Category | Door Prop Alarms & Annunciators | Accessories |
| Datasheet | /content/product-datasheets/400U-RMB.pdf | /content/product-datasheets/MC-4PAK.pdf |
Frequently Asked Questions
Which should you choose: the 400U-RMB or the MC-4PAK?
The 400U-RMB is the stronger choice when the installation site is standardized on 24VDC power infrastructure and requires an integrated door buzzer annunciator. The most concrete spec delta is input voltage: 400U-RMB at 24VDC versus MC-4PAK at 30VDC, directly affecting power supply compatibility and installation cost. Second, the 400U-RMB includes a built-in buzzer on a 1-gang wall plate; the MC-4PAK lists no equivalent, requiring a separate annunciator device if audible feedback is needed. Third, the 400U-RMB's 2½" x 4½" panel dimensions are consistent with standard access control enclosures, while the MC-4PAK's listed ¾" diameter is dimensionally inconsistent with a 4-door controller and should be verified against the manufacturer datasheet before specifying. Both units are otherwise equivalent on credential capacity (250,000), protocol support (OSDP, TCP/IP), door count (4), and warranty (lifetime). Specify the MC-4PAK only after confirming 30VDC supply availability and resolving the dimensional data discrepancy.
Can I use my existing 24VDC access control power supply with both the 400U-RMB and MC-4PAK?
No. The 400U-RMB is rated for 24VDC input and will work with a standard 24VDC access control power supply. The MC-4PAK requires 30VDC input, so a 24VDC supply is not compatible. You would need a dedicated 30VDC power source for the MC-4PAK, which should be factored into installation design and cost.
Does either controller include a built-in door buzzer, or do I need to add one separately?
The 400U-RMB specifies a built-in buzzer on a 1-gang wall plate form factor, so no separate annunciator is required for basic audible door feedback. The MC-4PAK does not list a built-in buzzer in the available specifications; a separate buzzer or annunciator device would need to be added if audible feedback is required.
Are the 400U-RMB and MC-4PAK compatible with the same access control software platforms?
Both controllers share the same communication protocols — OSDP for reader-level encrypted communication and TCP/IP for network integration — and both support HID-compatible credentials. However, neither product's available specifications list supported access control software platforms by name. Compatibility with your specific ACS should be confirmed directly with SDC Security Door Controls before purchase.
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