Allen-Bradley 1757-SRC1 1 m ControlLogix Redundancy Module Cable

Description

Key Technical Specifications

The 1757-SRC1 is a 1-meter redundancy module cable designed specifically to connect two 1757-SRM System Redundancy Modules in a ControlLogix redundant controller system. It is one member of the SRC cable family, which also includes 3 m, 10 m, 50 m, and 100 m versions.

Product Introduction

The Allen-Bradley 1757-SRC1 is a dedicated fiber-optic communication cable used in legacy ControlLogix redundancy systems. It provides the high-speed synchronization link between the primary and secondary 1757-SRM modules, allowing controller state information to be continuously mirrored for automatic switchover during a controller failure.

Unlike a standard Ethernet or industrial fiber cable, the 1757-SRC1 is engineered specifically for Rockwell Automation redundancy hardware. Using substitute fiber assemblies or incorrect connector types can prevent redundant synchronization or generate redundancy faults during commissioning.

1757-SRC1

1757-SRC1

Installation & Configuration Guide

Stage 1 – Pre-Installation Preparation (5 Minutes)

⚠️ Safety First

1. Notify plant operations.
2. Place the redundant system into a maintenance window.
3. Shut down both controller chassis if required by site procedures.
4. Wear an ESD wrist strap before handling fiber connections.

Required Tools

• Fiber cleaning kit
• ESD wrist strap
• Flashlight
• Cable labels
• Optical inspection scope (recommended)

Stage 2 – Remove Existing Cable (5 Minutes)

1. Verify redundancy synchronization is stopped.
2. Disconnect the cable from both 1757-SRM modules.
3. Install dust caps immediately.
4. Inspect connectors for contamination or damage.

⚠️ Never pull the fiber by the cable jacket. Always grip the connector body.

Stage 3 – Install the New Cable (10 Minutes)

1. Verify the cable is 1757-SRC1 (1 m).
2. Clean both fiber connectors before installation.
3. Connect one end to the primary 1757-SRM.
4. Connect the opposite end to the secondary 1757-SRM.
5. Route the cable away from high-voltage conductors.
6. Maintain the minimum bend radius specified for fiber-optic cable.

Installation Checklist

• ✔ Correct cable length
• ✔ Connectors fully seated
• ✔ No sharp bends
• ✔ Fiber cleaned before installation

Stage 4 – System Verification (10–15 Minutes)

1. Power both redundant chassis.
2. Verify both 1757-SRM modules initialize normally.
3. Confirm redundancy synchronization completes successfully.
4. Check controller diagnostics for communication errors.
5. Perform a controlled redundancy switchover test if permitted by plant procedures.

⚠️ Troubleshooting

• Redundancy synchronization failure: inspect connector cleanliness and cable routing.
• Communication timeout: verify both SRM modules are compatible and correctly configured.
• Intermittent faults: inspect the fiber for excessive bending or physical damage.

Frequently Asked Questions

Q1. What is the 1757-SRC1 used for?

It is a dedicated 1-meter fiber-optic cable that connects two 1757-SRM System Redundancy Modules, enabling continuous synchronization between the primary and secondary ControlLogix controllers.

Q2. Can I replace it with a standard fiber-optic patch cable?

No. The 1757- is designed specifically for the 1757-SRM redundancy architecture. Using an incorrect cable or connector type may prevent the redundancy system from synchronizing correctly.

Q3. What cable lengths are available?

Rockwell Automation offers multiple standard lengths:

• – 1 m
• 1757-SRC3 – 3 m
• 1757-SRC10 – 10 m
• 1757-SRC50 – 50 m
• 1757-SRC100 – 100 m

Q4. What is the maximum distance between redundant chassis?

Using standard SRC cables, redundant chassis can be separated by up to 100 m (300 ft). For greater distances, Rockwell recommends a custom multimode fiber installation meeting specific optical loss and connector requirements.

Q5. Is the 1757- still widely used?

Although intended for legacy ControlLogix redundancy systems, it remains in service in many facilities that continue to operate 1757-SRM-based redundant controller architectures. Replacement cables are commonly sourced as new surplus or tested used inventory.

Q6. What should I inspect before commissioning?

Verify:

• Correct catalog number ()
• Fiber connector cleanliness
• Proper routing without excessive bending
• Secure connector engagement
• Matching 1757-SRM module configuration
• Successful redundancy synchronization after startup

One of the most common field issues is contamination on fiber connectors. Even a small amount of dust can increase optical loss enough to prevent redundant controllers from synchronizing reliably. Always clean and inspect both connectors before powering the system.