Allen-Bradley 1770-CD Ruggedized DH+ Network Cable for Harsh Environments

Product Overview

Allen-Bradley 1770-CD Ruggedized DH+ Network Cable for Harsh Environments

The Allen-Bradley 1770-CD is a purpose-engineered twinaxial cable designed for Data Highway Plus (DH+) network communication in the most demanding industrial environments. Built to Rockwell Automation’s exacting specifications, this cable delivers consistent, low-noise signal transmission across PLC-5, SLC 500, and MicroLogix control architectures — even where temperature extremes, mechanical vibration, electromagnetic interference, and airborne contaminants would compromise lesser cabling solutions.

In continuous production environments — steel mills, petrochemical refineries, water treatment facilities, underground mining operations, and high-voltage power generation plants — network integrity is not optional. A single communication fault on a DH+ segment can cascade into unplanned downtime, safety interlocks failing to respond, or loss of supervisory visibility across an entire control zone. The 1770-CD is engineered to prevent exactly that. Its twinaxial construction provides inherent differential noise rejection, making it highly resistant to the radiated EMI generated by variable frequency drives, motor starters, arc furnaces, and high-current bus systems operating in close proximity.

The cable’s robust outer jacket withstands mechanical abrasion from cable trays, conduit routing, and repeated flexing during maintenance cycles. It maintains stable impedance characteristics across its rated temperature range, ensuring that DH+ token-passing protocol timing remains within specification whether the control cabinet is exposed to sub-zero startup conditions in an outdoor compressor station or the radiant heat of a glass furnace floor. This thermal stability is critical when the 1770-CD is used alongside Allen-Bradley 1771 I/O chassis, 1746 SLC 500 racks, or 1785 PLC-5 processors — all of which depend on reliable DH+ communication for coordinated control.

Rugged Specifications Table

Comprehensive Protection Solutions

The 1770-CD does not operate in isolation — it is the communication backbone that ties together an entire Allen-Bradley control architecture. In a typical DH+ segment, the cable connects Allen-Bradley 1785-L40B or 1785-L80B PLC-5 processors to remote I/O drops populated with 1771-OBD digital output modules and 1771-IFE analog input modules. Where the DH+ network bridges to a ControlLogix platform, the 1756-DHRIO communication module serves as the gateway, and the 1770-CD must maintain its impedance and shielding integrity all the way to the termination point to prevent reflections that corrupt token-passing arbitration.

In control cabinets where the 1770-CD is routed alongside 1606-XLP industrial power supplies, 700-CF Allen-Bradley safety relays, and 1492-J terminal blocks, proper cable separation and grounding of the twinaxial shield at a single point are essential. The cable’s foil-plus-braid shield construction provides the low-impedance ground path needed to suppress common-mode noise injected by nearby 22F PowerFlex variable frequency drives or 1336 PLUS II drives operating at high switching frequencies. When the 1770-CD is installed in hazardous-area panels alongside 1794-AENT FLEX I/O EtherNet/IP adapters or 1734 POINT I/O modules, maintaining the DH+ segment’s electrical integrity ensures that safety-critical status data reaches the supervisory layer without corruption or latency.

For installations requiring long-distance DH+ runs across plant floors, the 1770-CD is used in conjunction with 1770-KF2 or 1770-KF3 communication interface modules, which bridge RS-232 or RS-422 supervisory systems to the DH+ token ring. Proper termination using 1770-XP terminator plugs at both ends of the segment is mandatory to prevent standing waves that degrade communication reliability — particularly in high-vibration environments such as press lines, compressor halls, or rolling mills where cable connectors are subject to mechanical stress.

Application in Critical Infrastructure

In oil and gas upstream facilities, the 1770-CD forms the DH+ backbone connecting wellhead PLC-5 controllers to SCADA marshalling panels, transmitting real-time pressure, flow, and valve position data across distances that can exceed 1,500 meters in a single segment. The cable’s shielding performance is critical here: variable-speed pump drives, high-voltage switchgear, and cathodic protection rectifiers all generate broadband EMI that would corrupt unshielded network traffic.

In underground coal and metal mining operations, the 1770-CD is routed through armored conduit along conveyor drives and ventilation fan control panels. The combination of mechanical protection from the conduit and the cable’s own abrasion-resistant jacket ensures that DH+ communication to 1771 remote I/O racks remains uninterrupted even as the cable is subjected to ground movement, moisture ingress, and the vibration of continuous mining equipment.

Power generation facilities — whether coal-fired, gas turbine, or hydroelectric — rely on DH+ networks built around the 1770-CD to coordinate turbine governor controls, excitation systems, and balance-of-plant I/O. In these environments, the cable must perform reliably across temperature gradients from cold outdoor cable trays to hot turbine hall environments, and must resist the high-frequency interference generated by large synchronous generators and their associated excitation transformers.

Water and wastewater treatment plants use the 1770-CD to link SLC 500 and PLC-5 controllers managing pump stations, chemical dosing systems, and clarifier drives. The cable’s resistance to the humid, chemically aggressive atmosphere of a treatment plant — where chlorine, hydrogen sulfide, and ammonia vapors are present — is a key factor in its long service life in these installations.

Security & Quality FAQ

Q1: What warranty coverage is provided with the Allen-Bradley 1770-CD?
Every 1770-CD shipped by TOPNLMS carries a 12-month warranty covering manufacturing defects, shield continuity, and signal integrity performance. If the cable fails to meet DH+ network specifications within the warranty period under normal installation conditions, we provide replacement or full refund. Warranty claims are processed within 5 business days of receiving the returned item.

Q2: How is each unit tested before shipment?
All 1770-CD cables are inspected for jacket integrity, shield continuity, and conductor resistance before dispatch. Cables sourced from authorized distribution channels are verified against Rockwell Automation part number documentation. We do not ship untested or cosmetically damaged stock. A test report is available upon request for critical infrastructure procurement.

Q3: Is the 1770-CD compatible with both PLC-5 and SLC 500 DH+ networks?
Yes. The 1770-CD is the standard twinaxial cable specified by Rockwell Automation for all DH+ network segments, including those connecting PLC-5 processors, SLC 5/04 and SLC 5/05 controllers, MicroLogix 1500 units, and ControlLogix systems equipped with 1756-DHRIO modules. It is also compatible with DH-485 networks when used with appropriate interface modules. No hardware modification is required — the cable’s 78 Ω impedance matches the DH+ network specification directly.

Q4: Can TOPNLMS support long-term supply and emergency replacement needs?
Yes. TOPNLMS maintains stock of the 1770-CD and related Allen-Bradley DH+ network components to support both planned maintenance schedules and emergency breakdown situations. We understand that legacy DH+ networks in critical infrastructure cannot be taken offline for extended periods. Our standard lead time is 1–3 business days for in-stock items, with expedited same-day dispatch available for urgent plant breakdown orders. We also support procurement of associated components including 1770-XN connectors, 1770-XP terminators, and 1770-KF2 communication interfaces to provide a complete DH+ network restoration solution.