Allen-Bradley 1784 Data Highway Plus PC Card Modules – 1784-PKTX/B

Technical Dossier

Product Details And Specifications

Allen-Bradley 1784 Series Technical Notes

The Allen-Bradley 1784 series represents Rockwell Automation's primary communication interface card platform for Data Highway Plus (DH+), ControlNet, DeviceNet, and Remote I/O (RIO) network connectivity. These ISA, PCI, and PCMCIA-format cards are embedded in the control infrastructure of heavy industrial facilities worldwide — including petrochemical refineries, nuclear power stations, offshore platforms, and continuous-process chemical plants. The 1784 series serves as the physical bridge between engineering workstations running RSLinx, RSLogix 500, and RSLogix 5 and the Allen-Bradley PLC-5, SLC 500, and MicroLogix controller families. Installed base density is highest in facilities commissioned between 1990 and 2010, where DH+ remains the primary supervisory network and replacement of the communication layer is not economically viable.

The Evolution of 1784 Architecture

The 1784 series spans three distinct hardware generations tied to the evolution of PC bus standards and industrial network protocols.

Generation 1 — ISA Bus (1985–1998): Cards such as the 1784-KT and 1784-KTX used the 16-bit ISA slot, requiring manual IRQ and DMA configuration via DIP switches. These cards provided DH+ and DH-485 connectivity and were the standard interface for PLC-5 programming in the late 1980s and 1990s. ISA-based 1784 cards are now fully obsolete and require legacy PC hardware to operate.

Generation 2 — PCI Bus (1997–2010): The 1784-PKTX and 1784-PKTXD introduced PCI bus architecture, eliminating manual IRQ configuration and supporting plug-and-play installation under Windows NT/2000/XP. The 1784-PKTX/B (current SKU) is the B-revision of this card, incorporating firmware improvements for improved DH+ token-passing stability at 57.6 Kbps. The dual-port variant 1784-PKTXD supports simultaneous DH+ and DH-485 network connections from a single PCI slot.

Generation 3 — USB & Ethernet Migration (2005–present): Rockwell introduced the 1784-U2DHP USB-to-DH+ adapter as a software-compatible replacement for PCI cards, enabling connectivity from modern laptops and workstations without legacy PCI slots. For ControlNet, the 1784-PCIC and 1784-CPCIFM serve equivalent roles. The 1784 PCI card family is classified by Rockwell Automation as Discontinued; however, installed base demand sustains an active secondary market for maintenance and emergency replacement.

1784 Full Catalog & Functionalities (SKU List)

DH+ / DH-485 Communication Cards

• 1784-KT: ISA-bus DH+ interface card, single channel, IRQ/DMA configurable
• 1784-KTX: ISA-bus DH+ and DH-485 dual-protocol interface, 16-bit slot
• 1784-KTXD: ISA-bus dual-channel DH+ and DH-485, simultaneous network access
• 1784-PKTX: PCI-bus DH+ and DH-485 interface card, single channel, Rev A
• 1784-PKTX/B: PCI-bus DH+ and DH-485 interface card, single channel, Rev B — firmware-enhanced token stability
• 1784-PKTXD: PCI-bus dual-channel DH+ and DH-485, simultaneous dual-network operation
• 1784-U2DHP: USB-to-DH+ adapter, USB 1.1/2.0 host, software-compatible RSLinx replacement for 1784-PKTX

ControlNet Communication Cards

• 1784-PCIC: PCI-bus ControlNet interface card, single coax port, scheduled and unscheduled messaging
• 1784-PCICS: PCI-bus ControlNet interface, redundant coax (A/B) ports, safety-rated network access
• 1784-CPCIFM: CompactPCI ControlNet interface, fiber-optic media, for rack-mount workstation applications
• 1784-PCIC/A: Revision A of 1784-PCIC, earlier firmware baseline, functionally equivalent

DeviceNet Communication Cards

• 1784-PCD: PCI-bus DeviceNet scanner card, supports up to 64 nodes, master/slave configuration
• 1784-PCIDS: PCI-bus DeviceNet interface with extended diagnostic capability, dual-port

Remote I/O (RIO) Communication Cards

• 1784-KR: ISA-bus Remote I/O scanner, supports 1771 I/O chassis communication
• 1784-PKT: PCI-bus Remote I/O and DH+ combination interface card

PCMCIA / Portable Format

• 1784-PCMK: PCMCIA Type II DH+ and DH-485 card for laptop-based programming, 16-bit PC Card standard
• 1784-PCMK/B: Revision B of 1784-PCMK, updated firmware for Windows XP/Vista compatibility

Quality Control for the 1784 Range

The 1784 series cards present specific test challenges due to their dependence on PC bus timing, firmware revision compatibility with RSLinx Classic, and the sensitivity of DH+ token-passing logic to hardware faults.

DriveKNMS applies the following verification protocol to all 1784 units:

• Physical inspection: PCB examination for capacitor degradation, solder joint integrity, and connector pin condition on the DH+ RJ45/BNC port and PCI edge connector.
• Bus communication test: Card is seated in a verified PCI test bench running Windows XP SP3 with RSLinx Classic 2.59. Driver installation and device enumeration are confirmed.
• DH+ network loopback test: Card is connected to a live DH+ segment with a PLC-5 or SLC 5/04 controller. Token acquisition, message transmission at 57.6 Kbps, and sustained throughput over 30 minutes are verified.
• Firmware revision logging: Onboard firmware version is read and recorded. Cards with known problematic firmware revisions are reflashed where tooling permits.
• RSLinx driver compatibility check: Confirmed compatible with RSLinx Classic versions 2.51 through 4.11.