Product Overview
The Allen-Bradley 1746-C7 is a specialized, factory-terminated interconnect cable designed for linking multiple I/O chassis within the Allen-Bradley SLC 500 programmable controller system. This cable serves as the critical data and control highway that extends the processor’s I/O scanning and communication capabilities beyond the local chassis where the CPU resides. In SLC 500 systems, the processor module is typically housed in the left-most slot of a primary chassis. When the I/O requirements exceed the capacity of a single chassis, additional “expansion” or “remote” chassis are added. The Allen-Bradley 1746-C7 cable provides the physical link between these chassis, connecting the processor’s expansion port to the expansion port of the next chassis in the series. It carries the parallel data bus, timing signals, and power necessary for the processor to address, read inputs from, and write outputs to the I/O modules located in all connected racks, effectively making them appear as a single, contiguous I/O address space to the controller.This cable is an integral component for building scalable SLC 500 control systems, a workhorse platform for machine and process automation. The 1746-C7 is not a standard network cable; it is a proprietary, shielded, multi-conductor cable with specific connectors on each end that mate securely with the 50-pin expansion port headers on the SLC 500 chassis backplane. Its design ensures signal integrity over the relatively short distances (typically a few feet) between adjacent cabinets or racks, minimizing crosstalk and electrical noise that could corrupt I/O data. The use of a genuine Allen-Bradley 1746-C7 cable is crucial for system reliability, as an incorrect or poorly made substitute can lead to intermittent communication faults, I/O dropouts, or complete system failure. By enabling a clean and reliable expansion path, the 1746-C7 cable allows system designers to create control solutions that are precisely sized to the application’s I/O point count, optimizing both cost and panel layout. Its role, though often overlooked, is foundational to the stable operation of multi-rack SLC 500 installations.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1746-C7 |
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Product Type | SLC 500 System Expansion Interconnect Cable |
| Compatible System | Allen-Bradley SLC 500 Series |
| Function | Interconnects SLC 500 I/O chassis for local expansion |
| Connector Type (Each End) | 50-pin male header, keyed for proper orientation |
| Cable Length | Standard length is typically 7 feet (approx. 2.13 meters) |
| Cable Construction | Multi-conductor, shielded twisted pair |
| Shielding | Overall foil and/or braid shield for EMI/RFI protection |
| Maximum Number of Chassis in a Series | Limited by system; often up to 3 chassis including the CPU chassis (SLC 5/03, /04, /05) |
| Data Transfer | Parallel bus for high-speed I/O scanning |
| Power Conducted | Carries DC power for expansion chassis logic |
| Installation | Direct connection between chassis expansion ports |
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