Allen-Bradley 1784-PCMK Communication Card: Technical Overview, PCMCIA Architecture & Modern USB Alternative
The Allen-Bradley 1784-PCMK (Series A and Series B) was a Type II PCMCIA (Personal Computer Memory Card International Association) communication card manufactured by Rockwell Automation. Specifically, it provided portable notebook computers with a dedicated physical interface to communicate across Data Highway Plus (DH+), DH-485, and Remote I/O (RIO) networks for legacy PLC-5 and SLC 500 automation systems.
Consequently, the 1784-PCMK has become obsolete due to advancements in PC hardware architecture. Modern field laptops lack 68-pin PCMCIA/CardBus slots, and no 64-bit drivers exist for Windows 10 or Windows 11. While Rockwell originally suggested migrating to the 1784-U2DHP cable, that interface has also been discontinued, leaving maintenance teams requiring active USB hardware solutions.
Figure 1: Legacy Allen-Bradley 1784-PCMK Series A PCMCIA Card.
1. Allen-Bradley 1784-PCMK PCMCIA Architecture & System Compatibility
Historically, the PCMCIA standard defined compact expansion interfaces measuring 54.0 mm x 85.6 mm with a dual-row 68-pin connector. The 1784-PCMK card interfaced directly with industrial processors across the manufacturing floor:
- PLC-5 / 1771 Chassis Systems: Connected field service laptops directly to PLC-5/11, 5/20, 5/40, 5/60, and 5/80 processors for online ladder logic programming, diagnostics, and data table monitoring.
- SLC 5/04 Processors: Interfaced with Channel 1 (DH+) via 8-pin mini-DIN or 3-pin Phoenix connections for plant-wide supervisory control.
2. 1784-PCMK Cable Assemblies: 1784-PCM5 and 1784-PCM6 Pinouts
Furthermore, the 1784-PCMK card required specific detachable cable assemblies depending on the destination industrial protocol:
Legacy 1784-PCMK Protocol Differences: PCM5 vs. PCM6
- 1784-PCM5 Cable: Dedicated to Data Highway Plus (DH+) and Remote I/O (RIO) communication, branching to 3-pin Phoenix and 8-pin mini-DIN connectors.
- 1784-PCM6 Cable: Built for DH-485 networking, terminating in an RJ45 modular jack for SLC 5/01, 5/02, 5/03, and Fixed SLC controllers.
3. The Modern 1784-PCMK USB Alternative: ANC-120e Cable
In contrast to maintaining obsolete vintage laptops, the ANC-120e serves as a direct USB-to-DH+ cable interface. Specifically, it replaces the entire 1784-PCMK card and 1784-PCM5 cable assembly with a single plug-and-play USB device fully compatible with Windows 10 and Windows 11 (64-bit) running RSLinx Classic and RSLogix 5 / 500.
ANC-120e: USB to DH+ Cable
Direct USB alternative to 1784-PCMK and 1784-U2DHP. Connects modern laptops to PLC-5 and SLC 5/04 via RSLogix 5 & 500.
- • Windows 10 & 11 (64-bit) native support
- • Replaces PCMCIA card + 1784-PCM5 cable
- • Auto Baud & Auto Polarity detection
ANC-100e: DH+ to Ethernet Gateway
Permanent DIN-rail gateway bridging legacy DH+ networks directly to modern EtherNet/IP SCADA, Ignition, and PanelView Plus HMIs.
- • Standalone DH+ gateway architecture
- • Ignition, Kepware & FactoryTalk compatible
- • Lifetime Warranty & 30-Day Evaluation
4. Direct Comparison: 1784-PCMK vs. ANC-120e USB Converter
1784-PCMK Replacement Specification & Compatibility Matrix
| Feature / Specification | Automation Networks ANC-120e | Allen-Bradley 1784-PCMK (Legacy) | Allen-Bradley 1784-U2DHP (Legacy) |
|---|---|---|---|
| Host Connection | Standard USB 2.0 / USB 3.0 Port | PCMCIA Type II (16-bit / CardBus) | USB Type A (Discontinued) |
| OS Compatibility | Windows 10 & 11 (32-bit & 64-bit) | Windows 95 / 98 / 2000 / XP (32-bit only) | Windows XP / 7 (No native Win 11 support) |
| Cabling Required | Includes Phoenix & 8-Pin Mini-DIN | Requires separate 1784-PCM5 or PCM6 | Integrated mini-DIN cable |
| Baud Rate Detection | Automatic (57.6k, 115.2k, 230.4k) | Manual configuration in RSLinx | Manual software configuration |
| Availability & Lifecycle | In Stock • Brand New with Warranty | Discontinued / Obsolete Surplus | Discontinued / High-priced Surplus |
| Price & Warranty | $995 USD (Lifetime Hardware Warranty) | $800–$1,500 USD (Used / As-Is on eBay) | $2,500–$3,500 USD (Used / Surplus Market) |
Upgrade Your PLC Maintenance Toolkit with Active Hardware
Therefore, instead of sourcing refurbished PCMCIA cards or keeping vintage laptops in service, Automation Networks delivers reliable, field-tested communication hardware with same-day shipping:
- ANC-120e ($995 USD): Portable USB-to-DH+ programming cable for Windows 10 & 11 field laptops running RSLogix 5 and RSLogix 500. Technical review available on The Automation Blog (Show #58).
- ANC-100e ($1,195 USD): Permanent DIN-rail gateway bridge connecting DH+ racks directly to modern plant-wide EtherNet/IP networks. Video demonstration available on The Automation Blog (Show #2).