Allen-Bradley 1784-PCMK – PCMK Communication Card | ControlLogix / PLC-5 DH+ & RS-232 Interface
Engineering Background
The 1784-PCMK is a PC-based communication interface card developed by Rockwell Automation / Allen-Bradley for integration with Data Highway Plus (DH+) networks and RS-232 serial devices. Designed for use with PLC-5, SLC 500, and ControlLogix platforms, this card enables direct PC-to-PLC communication for programming, monitoring, and data acquisition tasks in industrial automation environments.
Product Positioning
The 1784-PCMK serves as a critical bridge between engineering workstations running RSLogix / RSLinx software and legacy or current Allen-Bradley PLC networks. It is the preferred interface card for facilities maintaining DH+ infrastructure alongside modern ControlLogix systems, eliminating the need for protocol converters or third-party gateways.
Complete Technical Specifications
| Part Number | 1784-PCMK |
| Manufacturer | Allen-Bradley / Rockwell Automation |
| Card Type | PC Communication Interface Card (ISA/PCMCIA) |
| Network Protocol | Data Highway Plus (DH+) |
| Serial Interface | RS-232C |
| Compatible Platforms | PLC-5, SLC 500, ControlLogix (via DH+ bridge) |
| Software Compatibility | RSLinx Classic, RSLogix 5, RSLogix 500 |
| Operating System | Windows XP / 7 / 10 (32-bit driver support) |
| DH+ Baud Rate | 57.6 kbps (standard DH+ network rate) |
| Node Address Range | 0–77 (octal) |
| Power Supply | Supplied via host PC bus |
| Operating Temperature | 0°C to 60°C (32°F to 140°F) |
| Storage Temperature | -40°C to 85°C |
| Weight | 240 g |
| Certifications | UL Listed, CE Marked |
| Country of Origin | USA |
Proven Application Environments
- Automotive Manufacturing: PLC-5 programming and online monitoring via DH+ network on assembly lines
- Oil & Gas: Remote diagnostics and data logging from SLC 500 controllers in hazardous-area panels
- Water Treatment: SCADA integration with legacy Allen-Bradley PLC networks using RSLinx OPC server
- Food & Beverage: Recipe download and batch control via PC-to-PLC DH+ communication
- Power Generation: Maintenance workstation connectivity for ControlLogix systems bridged over DH+
- Discrete Manufacturing: Real-time HMI data acquisition and alarm management via RSLinx Classic
Engineering Advantages
- Native DH+ Protocol Support: No protocol conversion overhead — direct hardware-level DH+ communication ensures deterministic, low-latency data exchange
- Dual Interface: Simultaneous DH+ network access and RS-232 serial connectivity from a single card slot
- RSLinx Certified: Fully supported by Rockwell Automation RSLinx Classic driver stack — plug-and-play configuration with auto node detection
- Legacy System Longevity: Extends the operational life of PLC-5 and SLC 500 installations without requiring costly network upgrades
- Stable Driver Ecosystem: Mature, well-documented Windows driver with extensive field deployment history across global industrial sites
- Compact Form Factor: Minimal PC slot footprint suitable for industrial panel PCs and ruggedized workstations
System Architecture & Signal Flow
The 1784-PCMK installs into the host PC and presents as a DH+ network node (configurable address 0–77 octal). RSLinx Classic detects the card via its dedicated WinSock driver and establishes a virtual communication path to all DH+ nodes on the network segment. The RS-232 port operates independently, supporting DF1 full-duplex or half-duplex protocol for point-to-point PLC connections.
Typical Signal Flow: Engineering PC → 1784-PCMK Card → DH+ Trunk Cable (Belden 9463 or equivalent) → PLC-5 / SLC 500 / ControlLogix DH+ Bridge → Target Controller
The card supports multi-node topologies with up to 64 nodes per DH+ segment, enabling simultaneous access from multiple workstations when used with RSLinx Enterprise or OPC DA server configurations.
Sourcing & Quality Verification
- Source: Verified surplus and refurbished stock from decommissioned industrial facilities and authorized distributors
- Inspection Protocol: Each unit undergoes visual inspection, functional power-on test, and DH+ communication verification prior to listing
- Authenticity: All units carry original Allen-Bradley / Rockwell Automation part markings and serial numbers — no counterfeit or remarked components
- Packaging: Anti-static ESD packaging with foam cushioning for safe international transit
- Warranty: 90-day functional warranty against DOA or communication failure under normal operating conditions
- Documentation: Original Rockwell Automation installation manual and driver CD available upon request
Procurement Process
- Confirm Compatibility: Verify your host PC has an available ISA/PCMCIA slot and runs a supported Windows OS version
- Place Order: Add to cart and complete checkout — we accept T/T bank transfer, PayPal, and major credit cards
- Order Confirmation: Receive stock confirmation and proforma invoice within 1 business day
- Shipping: Units ship within 2–3 business days via DHL / FedEx with full tracking; express options available
- Technical Support: Post-delivery RSLinx driver configuration support available via email at support@konmask.com
For bulk orders (>5 units), OEM procurement, or project-based sourcing, contact us directly for volume pricing and lead time confirmation.
Technical FAQ
Q: Is the 1784-PCMK compatible with Windows 10 64-bit?
A: The 1784-PCMK requires 32-bit Windows drivers. On Windows 10 64-bit systems, driver compatibility depends on RSLinx Classic version and may require legacy driver workarounds. We recommend confirming with your RSLinx version before purchase.
Q: Can this card communicate with ControlLogix over DH+?
A: Yes, via a 1756-DHRIO or 1756-DH485 bridge module installed in the ControlLogix chassis, the 1784-PCMK can access ControlLogix controllers over a DH+ network segment.
Q: What cable is required for DH+ connection?
A: Belden 9463 (blue hose) is the standard DH+ cable. The 1784-PCMK connects via a standard DH+ connector (1770-CD cable assembly recommended).
Q: Does this unit come with RSLinx software?
A: RSLinx Classic software is licensed separately by Rockwell Automation. We can supply the hardware card; software licensing must be obtained through your Rockwell distributor or existing site license.
Q: What is the maximum DH+ network length?
A: DH+ supports up to 3,048 m (10,000 ft) total trunk length with proper termination resistors at each end of the network segment.
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