1747-KE DH-485 to RS-232C Interface Module (SLC 500)

Overview

The Allen-Bradley 1747-KE is a DH-485-to-RS-232C interface module for Allen-Bradley SLC 500 chassis, built to bridge a DH-485 network to devices that communicate using the DF1 protocol. It resides directly in the SLC 500 backplane, making it a natural fit for linking a remote DH-485 network back to a central host over a modem connection without adding a separate standalone converter.

As a legacy but still widely deployed SLC 500 communication module, the 1747-KE remains a common spare-parts requirement for facilities maintaining existing Allen-Bradley control systems. Seven Star LLC supplies the 1747-KE to industrial facilities across Oman and the GCC.

Operating Principle

The 1747-KE sits in an SLC 500 chassis slot and translates communication between a DH-485 network and DF1-protocol devices, effectively acting as a bridge so that a DF1-based host or modem link can reach nodes on a remote DH-485 network. It offers three 9-pin D-sub connectors: a CONFIG port for module setup, a DF1 port for the host-side connection, and a DH-485 port for the local network side (requiring a 1747-AIC link coupler when connecting to a multi-node DH-485 network).

Engineering Design of the Allen-Bradley 1747-KE

Both the CONFIG and DF1 ports support selectable baud rates of 300, 600, 1200, 2400, 4800, 9600, and 19200 bps, with the DH-485 port operating at the same rate options, giving flexibility to match existing network speed and modem capability. Each port can be configured for RS-232/423, RS-422, or RS-485 electrical standards, and the module draws its power directly from the SLC 500 backplane rather than requiring a separate power supply.

Key Features

• Bridges DH-485 networks to DF1-protocol devices
• Fits directly into an SLC 500 chassis slot, backplane-powered
• Three 9-pin D-sub ports: CONFIG, DF1, and DH-485
• Selectable baud rates from 300 to 19200 bps on all ports
• Configurable RS-232/423, RS-422, or RS-485 electrical standards
• Compatible with SLC 500 fixed, 5/01, 5/02, 5/03, 5/04, and 5/05 processors
• Supports remote DH-485 network access via modem link
• Requires 1747-AIC link coupler for multi-node DH-485 connections

Industrial Applications

The 1747-KE is used to maintain and extend legacy SLC 500-based control systems across Muscat, Sohar, and Salalah, particularly where a remote DH-485 network segment needs to communicate back to a central SCADA host or engineering workstation over a modem link rather than a direct hardwired connection. It remains a relevant spare part for facilities that have not yet migrated away from SLC 500 architecture.

Across the GCC’s process and utility sectors, the 1747-KE supports ongoing maintenance of established Allen-Bradley control installations where replacing the entire control platform isn’t justified, letting engineering teams keep remote DH-485 devices connected and communicating through existing infrastructure.

Technical Specifications

Confirming the Right Module

The 1747-KE is identified by the catalogue number on its side label, together with the series letter and firmware revision. When replacing a failed module, record these from the existing unit and note its configuration settings, since a replacement must be set up to match the original before it will communicate. Check as well:

• SLC 500 processor type and the chassis slot used
• Whether the DH-485 side connects through a 1747-AIC link coupler
• Baud rates configured on the DF1 and DH-485 sides
• The modem or host device on the DF1 port and its cable wiring

1747-KE Installation and Configuration

Power down the chassis before inserting or removing the module, and seat it firmly in its slot. Configuration is carried out through the CONFIG port with a terminal connected, where the DF1 port parameters (baud rate, parity, handshaking, station address and duplex mode) and the DH-485 node address and baud rate are set. The DH-485 node address must be unique on the network and the baud rate must match the other nodes. After configuration, save the settings and confirm the status indicators show normal operation before connecting the host.

Integration with SCADA and Host Systems

On the host side the Allen-Bradley 1747-KE presents a DF1 serial link, which is supported by many SCADA packages, programming tools and telemetry RTUs. This makes the module a practical way to reach remote SLC 500 sites over leased lines, radio modems or serial-to-Ethernet converters without changing the PLC program. Full-duplex DF1 is typical for point-to-point links, while half-duplex operation suits multi-drop modem networks where a master polls several remote stations.

Troubleshooting Common Problems

• No communication with the host – mismatched baud rate, parity or DF1 mode, or an incorrect cable pinout on the DF1 port
• DH-485 nodes not seen – duplicate node address, wrong maximum node setting, or missing termination at the link couplers
• Intermittent drop-outs – noise on long serial runs, poor grounding, or modem timeouts set too short

Legacy Support in Oman and the GCC

Many water, utility and process sites in the region still run SLC 500 systems with remote DH-485 segments. Keeping a tested spare interface module on site shortens outages while a longer-term migration plan is prepared. Seven Star LLC supplies the 1747-KE and related SLC 500 spares, and our team helps confirm the catalogue number and series before dispatch.

When a site is planning a migration away from SLC 500, the same information gathered for a replacement – node addresses, baud rates, host polling configuration and modem details – forms a useful baseline for the new communication design, so it is worth recording carefully during any module change.

Request a Quote for 1747-KE DH-485 to RS-232C Interface Module (SLC 500)

Contact Seven Star LLC for a quotation and availability on the Allen-Bradley 1747-KE DH-485/RS-232C interface module and other SLC 500 spare parts across Oman and the GCC.

Browse the full Allen-Bradley range or see more PLC & I/O Cards products supplied by Seven Star LLC in Oman and the GCC.