Why the 1756-RMC1 Belongs in Your Redundancy Build
Engineers designing ControlLogix redundant controller systems face a common gap: the chassis and redundancy modules arrive without the fiber optic link that ties them together. The Allen-Bradley 1756-RMC1 closes that gap. This one-meter fiber optic cable connects 1756-RM2 and 1756-RM2K redundancy modules, and it is the shortest option in the Bulletin 1756-RMCx cable family. When cabinet space is tight, that shorter run matters.
This is not a generic patch cord. It is a purpose-built communication link for a specific architecture, and treating it as anything less invites trouble during commissioning.
Key Parameters That Shape Your Design
Length and Routing
At one meter (3.28 feet), the 1756-RMC1 suits compact redundant pairs mounted close together. Longer runs belong to other members of the 1756-RMCx series. Plan your module spacing around this fixed length before you finalize the enclosure layout.
Fiber Optic Construction
The cable carries a single channel over optical fiber. Because it contains optical fibers, it must not be forced into sharp bends. An LC connector coupler can hold the cable in a safe curve and allows connection or disconnection without pulling the module from the chassis. This detail saves time during maintenance windows.
Wire and Environmental Ratings
The 1756-RMC1 uses 20 AWG wire. It operates in ambient temperatures from 0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit). The enclosure is listed as none, so the cable relies on the surrounding cabinet for mechanical protection.
Physical Dimensions
Shipping dimensions are 5.51 x 4.41 x 5.71 inches. Confirm clearance below each module, because the cable connects at the bottom of the module in a downward orientation.
Where This Cable Earns Its Place
Redundant Controller Pairs
A ControlLogix redundant controller system requires one or two of these cables. The fiber link synchronizes the redundancy modules. Without it, the pair cannot function as intended.
Standard and Extreme-Environment Modules
The 1756-RMC1 is compatible with both standard and extreme-environment modules. That flexibility simplifies spare-part planning across mixed installations.
Compact Control Cabinets
When two redundancy modules sit side by side, the one-meter length removes excess cable that would otherwise need coiling and strain relief. Less slack means fewer snag points.
Installation Guidance
Remove the protective caps before connecting the cable. Route it through areas free from traffic that could run over, abrade, or cut it. Keep bends gentle and use the LC connector coupler where needed. The cable plugs into the bottom of the module, pointing downward, so leave service clearance beneath the chassis.
Remember that redundancy modules and chassis do not ship with these connectors. Order them separately before system assembly begins.
Reliability and Fault Tolerance
A redundant fiber cable system can tolerate one of multiple faults on a single channel. If a fault occurs on both channels, network operation becomes unpredictable. This is why inspection matters. Check the cable periodically for abrasion, kinks, or connector damage, and follow the manufacturer’s safety manual for all maintenance activities.
Compatibility and Integration
The 1756-RMC1 belongs to the ControlLogix platform and the Bulletin 1756-RMCx cable series. It works with 1756-RM2 and 1756-RM2K redundancy modules. Because redundancy modules and chassis do not include these connectors, verify your bill of materials before assembly. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
What to Confirm Before You Buy
Check three things: your module pair (1756-RM2 or 1756-RM2K), your required cable length, and your cabinet clearance below the modules. If one meter is too short, other lengths in the 1756-RMCx series may fit better. SpareTechPLC supplies genuine Allen-Bradley automation parts and can help you match the right cable to your redundancy architecture.
Frequently Asked Questions
Which modules does the 1756-RMC1 connect?
It connects Allen-Bradley ControlLogix 1756-RM2 and 1756-RM2K redundancy modules in redundant controller systems.
How long is this cable?
It measures one meter, or 3.28 feet. It is the shortest cable available for these modules.
Can I use it with extreme-environment modules?
Yes. The cable is compatible with both standard and extreme-environment modules.
How many cables does a redundant system need?
Building a ControlLogix redundant controller system requires one or two of these cables.
What should I check before installation?
Remove the protective caps, avoid sharp bends, and keep the cable away from areas where it could be run over, abraded, or cut.
