Allen-Bradley 1747-UIC PLC Interface Converter – SLC 500 Series

Allen-Bradley 1747-UIC: USB-to-DH-485 Interface Converter in SLC 500 Control Architecture

The Allen-Bradley 1747-UIC is a dedicated USB-to-DH-485 protocol bridge engineered by Rockwell Automation for direct PC-to-PLC communication within SLC 500 and MicroLogix control networks. Unlike generic serial adapters, the 1747-UIC implements the full DH-485 token-passing protocol stack in firmware, ensuring deterministic bus arbitration and correct multi-drop node addressing without relying on the host PC’s CPU for timing-critical operations. In distributed manufacturing environments where SLC 5/03, 5/04, and 5/05 processors manage discrete I/O, motion sequencing, and process interlocks, the 1747-UIC serves as the sole certified programming and diagnostic gateway between engineering workstations and the DH-485 segment.

The converter draws power exclusively from the USB bus (500 mA max draw, typically under 200 mA in operation), eliminating the need for an external 24 VDC supply at the panel. Its internal optical isolation barrier — rated at 500 V DC working isolation — decouples the USB ground reference from the DH-485 bus ground, preventing ground-loop-induced data corruption that is common in large steel-frame panels where multiple earth references exist across cabinet rows.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The 1747-UIC’s internal architecture separates into three functional domains: the USB device controller, the protocol translation engine, and the DH-485 transceiver stage.

USB Device Controller: The converter enumerates as a CDC (Communications Device Class) virtual COM port on the host OS, which means no proprietary kernel driver is required on Windows 10/11 — the OS-native usbser.sys driver handles enumeration. RSLinx Classic then binds to the virtual COM port via its DF1 or DH-485 driver configuration. This architecture avoids the latency penalties associated with WDM kernel-mode custom drivers and keeps the USB transaction overhead below 1 ms per frame at Full-Speed.

Protocol Translation Engine: The embedded microcontroller handles the complete DH-485 token-passing state machine: token rotation, solicit-successor frames, reply-to-solicit frames, and data frames. The firmware enforces the 87.5 µs inter-character timeout and the 10 ms token hold time defined in the DH-485 specification. This means the host PC’s USB polling interval (1 ms at Full-Speed) does not introduce protocol violations on the DH-485 bus — the converter buffers and re-times frames internally before transmission.

EMC Design & Optical Isolation: The 500 V DC optical isolation barrier uses high-speed optocouplers with a propagation delay under 1 µs, which is well within the DH-485 bit-time at 19,200 bps (52 µs). The isolation prevents common-mode transients — typically 1–5 kV spikes in heavy industrial environments with VFDs and contactors — from propagating back to the USB port and damaging the host laptop. The DH-485 transceiver stage uses a differential RS-485 driver with ±15 kV ESD protection on the A/B lines, compliant with IEC 61000-4-2 Level 4.

Bus Termination Considerations: The 1747-UIC does not include an internal 120 Ω termination resistor on the DH-485 side. In networks with cable runs exceeding 30 m or baud rates at 19,200 bps, external termination at both physical ends of the bus is required to suppress reflections. The AIC+ (1761-NET-AIC) provides switchable termination for multi-drop topologies where the 1747-UIC is inserted mid-segment.

System Integration Benefits

• Deterministic Token-Passing Arbitration: The 1747-UIC manages the full DH-485 token rotation internally, so PLC scan-cycle jitter on the SLC 500 processor does not affect bus access timing. Programming sessions and online monitoring remain stable even when the processor is under high I/O load.
• Zero External Power Dependency: Bus-powered operation means field engineers can connect to a live panel without locating a 24 VDC auxiliary supply. This reduces commissioning time and eliminates one potential failure point in the connection chain.
• Ground-Loop Immunity: The 500 V DC optical isolation barrier eliminates ground-loop currents between the PC chassis ground and the panel earth bus — a common source of intermittent communication faults in large steel-frame enclosures with multiple grounding points.
• Multi-Drop Network Compatibility: A single 1747-UIC can address all 32 nodes on a DH-485 segment simultaneously. RSLinx Classic’s DH-485 driver maps each node to a separate logical device, enabling concurrent online monitoring of multiple SLC 500 processors without rewiring.
• Legacy System Longevity: For SLC 500 installations that cannot be migrated to ControlLogix or CompactLogix due to process constraints, the 1747-UIC extends the serviceable life of the DH-485 network by providing a modern USB interface that works with current-generation laptops lacking RS-232 ports.
• Diagnostic Transparency: RSLinx Classic’s DH-485 driver exposes node status, token rotation counts, and error frame statistics through its diagnostics tab when used with the 1747-UIC. This allows maintenance engineers to identify failing nodes or cable faults without a dedicated protocol analyzer.
• Software Ecosystem Compatibility: The converter is compatible with RSLogix 500, RSLogix Micro, and Studio 5000 Logix Designer (via legacy DH-485 driver), as well as third-party SCADA packages that use RSLinx Classic as an OPC DA server. No additional middleware or gateway hardware is required.
• Reduced Commissioning Risk: Because the 1747-UIC is a Rockwell Automation OEM product with a published firmware revision history, it is accepted by end-user site safety reviews without the additional qualification testing that third-party USB-to-RS-485 adapters typically require in regulated industries (food & beverage, pharmaceutical, oil & gas).

Quality Assurance & Global Logistics

Every 1747-UIC unit dispatched from our Xiamen, China facility is a genuine Rockwell Automation OEM product sourced through verified industrial distribution channels. Each unit undergoes a structured pre-shipment inspection covering label authenticity, housing integrity, connector condition, USB enumeration verification, and DH-485 signal continuity test. Units that do not pass all inspection stages are quarantined and not shipped.

Our 12-month warranty covers manufacturing defects and functional failures under normal operating conditions. DOA (Dead on Arrival) units are replaced within 7 business days of confirmed receipt. Warranty claims require photographic evidence of the defect and the unit’s serial number.

Logistics Capabilities from Xiamen, China:

• Express air freight: DHL Express, FedEx International Priority, UPS Worldwide Express — typical transit 3–5 business days to Europe, North America, Southeast Asia
• Economy air: SF International, EMS — 7–14 business days
• Sea freight: available for bulk orders of 20+ units; transit 18–35 days depending on destination port
• Export documentation: commercial invoice, packing list, certificate of origin (CO), and HS code declaration (8537.10) provided with every shipment
• In-stock orders are dispatched within 1–3 business days of payment confirmation

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.