Allen-Bradley 1770-KFD Industrial Network Interface for DH+ Systems: Bridging the Industrial Data Link
In modern smart manufacturing environments, seamless data flow between field devices and supervisory systems is no longer optional — it is the foundation of operational efficiency. The Allen-Bradley 1770-KFD is a purpose-built Data Highway Plus (DH+) communication interface module designed to establish a reliable, high-integrity data link between host computers, programming terminals, and Allen-Bradley PLC controllers operating on the DH+ network. Whether you are integrating legacy control systems into a contemporary SCADA architecture or expanding an existing DH+ network segment, the 1770-KFD delivers the protocol-level connectivity that industrial automation demands.
The 1770-KFD connects directly to a PC or programming workstation via a serial interface, translating host-side communication into the DH+ token-passing protocol used across Allen-Bradley PLC-5, SLC 500, and MicroLogix controller families. This makes it an indispensable gateway component for engineers who need to upload/download ladder logic programs, monitor real-time register values, execute remote diagnostics, and push configuration changes — all without interrupting live production processes.
Compatibility & Integration Notes
| Attribute |
Specification |
| Communication Protocol |
Data Highway Plus (DH+) |
| Interface Type |
Serial (RS-232) to DH+ Network |
| Network Baud Rate |
57.6 Kbps (DH+ selectable) |
| Compatible PLC Families |
PLC-5, SLC 500, MicroLogix (DH+ port) |
| Network Topology |
Token-passing bus (DH+ architecture) |
| System Application |
SCADA integration, HMI connectivity, remote programming, diagnostics |
| Network Compatibility |
Allen-Bradley DH+ (1770 series network) |
| Warranty |
warranty terms confirmed during quotation | Global availability subject to RFQ confirmation |
Connected Automation Data Flow
The value of the Allen-Bradley 1770-KFD becomes most apparent when you trace the complete data path across a typical industrial site. At the field level, sensors and actuators feed real-time process signals into Allen-Bradley PLC-5 controllers or SLC 5/04 processors equipped with native DH+ ports. These controllers execute ladder logic, manage I/O states, and generate process data that must be communicated upstream to supervisory systems.
The 1770-KFD acts as the critical bridge at this junction. Installed between the host workstation and the DH+ network trunk, it handles the token-passing arbitration and packet framing required by the DH+ protocol, allowing RSLogix 5 or RSLogix 500 programming software to communicate transparently with the target controller. In parallel, SCADA platforms such as FactoryTalk View SE or Wonderware InTouch can leverage the same DH+ data path — via RSLinx Classic configured with the 1770-KFD driver — to poll data table values, update HMI tag databases, and trigger alarm conditions based on live PLC register states.
For remote I/O architectures, the 1770-KFD complements Allen-Bradley 1771 I/O chassis systems by providing the programming and monitoring access point that keeps the remote rack visible to the control room. Engineers working with MicroLogix 1100 or MicroLogix 1500 controllers that include a DH+ communication port can use the 1770-KFD to integrate these smaller controllers into the same network segment as larger PLC-5 systems, creating a unified data collection layer without requiring a full network redesign.
At the drive and motion layer, variable frequency drives such as the Allen-Bradley PowerFlex 700 — when equipped with a DH+ communication adapter — can be monitored and parameterized through the same 1770-KFD gateway, enabling centralized speed reference management and fault logging directly from the SCADA historian. This eliminates the need for separate drive commissioning tools during routine maintenance windows.
Edge gateway devices and data concentrators that aggregate DH+ network traffic for forwarding to MES or ERP systems also rely on stable, low-latency DH+ access — precisely what the 1770-KFD provides. When combined with an Allen-Bradley 1756-DHRIO ControlLogix bridge module in a larger plant topology, the 1770-KFD can serve as the local programming access point on a DH+ subnet while the DHRIO handles inter-network routing to the ControlLogix backplane, giving engineers flexible access at every network tier.
Solving Data Isolation in Industrial Sites
One of the most persistent challenges in brownfield industrial environments is protocol fragmentation. A plant floor may simultaneously operate DH+ networks for legacy PLC-5 systems, EtherNet/IP segments for newer ControlLogix controllers, and DeviceNet drops for distributed I/O — each forming an isolated data island with no native path to the plant historian or corporate MES. The Allen-Bradley 1770-KFD directly addresses the DH+ segment of this challenge by providing a standardized, software-accessible interface that eliminates the need for proprietary hardware dongles or obsolete ISA-bus cards.
For remote monitoring and diagnostics, the 1770-KFD enables engineers to connect to DH+ nodes from any workstation running RSLinx Classic, regardless of physical location when combined with appropriate remote access infrastructure. This capability is critical for multi-site manufacturers who need to push firmware updates, retrieve fault logs, or adjust PLC parameters without dispatching field technicians — reducing mean time to repair (MTTR) and keeping production lines running.
Production line transparency is another key benefit. By making DH+ data accessible to SCADA and HMI platforms, the 1770-KFD enables real-time OEE dashboards, shift-based production reports, and predictive maintenance triggers based on PLC counter and timer values. Data that was previously locked inside the controller’s data table becomes a live feed for continuous improvement initiatives.
System expansion is equally straightforward. As plants add new DH+ nodes — whether additional PLC-5 racks, SLC 500 processors, or DH+-capable HMI panels — the 1770-KFD scales with the network without requiring changes to the host interface configuration. Its plug-and-play compatibility with RSLinx Classic means new nodes are recognized automatically once connected to the DH+ trunk.
Industrial Connectivity FAQ
Q1: What is the maximum communication latency on a DH+ network using the 1770-KFD?
DH+ networks using the 1770-KFD operate at selectable baud rates up to 57.6 Kbps with token-passing arbitration. Typical message round-trip latency on a lightly loaded network is under 50 ms, making it suitable for supervisory data collection and remote programming tasks. It is not designed for deterministic real-time control loops, which are better served by ControlNet or EtherNet/IP.
Q2: Is the 1770-KFD compatible with both PLC-5 and SLC 500 controllers on the same DH+ segment?
Yes. The DH+ protocol supports mixed-node networks, and the 1770-KFD can communicate with PLC-5, SLC 5/04, SLC 5/05 (with DH+ port), and MicroLogix controllers that include a DH+ channel — all on the same network segment. RSLinx Classic manages node addressing and driver configuration for each device type.
Q3: How does ZYPLC verify the 1770-KFD before shipment?
Every Allen-Bradley 1770-KFD unit supplied by ZYPLC undergoes pre-shipment functional testing, including DH+ communication verification and interface integrity checks. Units are shipped with a warranty terms confirmed during quotation covering manufacturing defects and communication failures. Test records are available upon request for quality-critical applications.
Q4: Can the 1770-KFD be used to expand an existing DH+ network to additional SCADA or HMI nodes?
Absolutely. The 1770-KFD is the standard interface for adding PC-based SCADA workstations, HMI configuration terminals, and data historian clients to an existing DH+ network. Multiple 1770-KFD units can be deployed across different workstations on the same DH+ segment, each assigned a unique node address, enabling parallel access for programming, monitoring, and data logging without network conflicts.
