Product Overview

The Allen-Bradley 1747-CP3 Programmer Cable is an RS-232 serial communication cable designed for programming, configuration, and communication with Allen-Bradley SLC 500 programmable logic controllers. Manufactured by Rockwell Automation, this cable provides a direct serial connection between a compatible SLC processor and a computer or other data terminal equipment (DTE).

In industrial automation systems, a reliable programming connection is essential for controller configuration, troubleshooting, program maintenance, and equipment commissioning. The 1747-CP3 provides the physical communication link required for these tasks, allowing engineers and maintenance technicians to access compatible SLC controller serial ports.

The cable is primarily associated with SLC 5/03 and SLC 5/04 modular processors. It is also identified in SLC 500 system documentation for use with SLC 5/05 processors. Its RS-232 interface and 9-pin D-shell connector arrangement make it suitable for supported serial programming and communication applications.

The 1747-CP3 has a nominal cable length of 10 feet, approximately 3 meters. Its connector configuration includes a right-angle 9-pin female D-shell connector at one end and a straight 9-pin female D-shell connector at the other. The internal wiring arrangement supports the intended RS-232 connection between the controller and a DTE device.

This cable is a dedicated programming accessory rather than a general-purpose serial extension cable. Its connector arrangement and internal wiring are important to proper communication. Substituting an ordinary straight-through serial cable may not provide the required connection.

The 1747-CP3 is now discontinued. It remains relevant to facilities maintaining legacy SLC 500 installations, where original programming accessories may be needed for controller maintenance and troubleshooting.

Technical Specifications

Note: The 3 kg figure is the supplied shipping weight, not the confirmed net weight of the cable itself. Packaging and shipment contents may affect the final shipping weight.

Function and Working Principle

The 1747-CP3 provides an electrical communication path between a compatible SLC controller and an external DTE device. It uses RS-232 serial signaling, allowing programming software and supported communication applications to exchange data with the controller.

1. RS-232 Serial Communication

RS-232 is a serial communication standard commonly used in industrial equipment and legacy computer interfaces. It transfers data between connected devices through defined signal lines.

The 1747-CP3 is designed for the RS-232 channel on compatible SLC processors. Once connected correctly, the cable allows a computer or other supported DTE device to communicate with the controller.

Communication depends on the correct port, cable wiring, serial settings, and compatible software.

2. PLC Programming Connection

During commissioning or maintenance, engineers may need to connect a programming computer to an SLC processor. The 1747-CP3 provides the physical connection for supported programming operations.

Typical tasks include:

• Uploading an existing controller program.
• Downloading an approved program.
• Monitoring controller operation.
• Reviewing data tables.
• Checking processor status.
• Troubleshooting communication-related issues.

Actual functions depend on the controller model, programming software, firmware, and communication configuration.

3. Connector and Wiring Arrangement

The cable uses two 9-pin female D-shell connectors. One connector is designed with a right-angle housing, while the other has a straight housing.

The internal wiring includes the signal connections and jumper arrangement required for the intended DTE communication configuration. This is important because RS-232 cables are not all wired in the same way.

When replacing the cable, technicians should confirm both connector orientation and wiring compatibility. A cable with matching connector shapes may still be electrically unsuitable.

4. Data Exchange Between Devices

Once the connection is established, the computer and PLC can exchange serial data according to the supported communication protocol and software settings.

The cable itself does not perform protocol conversion, program execution, or signal processing. It provides the physical communication path, while the controller and connected software handle the actual data exchange.

5. Maintenance and Diagnostic Access

The cable can support maintenance activities by providing access to the controller’s serial communication channel. This is useful when engineers need to investigate program behavior, review controller information, or perform approved configuration changes.

A stable physical connection is especially important during program transfer and diagnostic operations. Loose connectors, damaged conductors, or incorrect cable wiring may interrupt communication.

Role in Industrial Control Systems

The 1747-CP3 is an accessory used within Allen-Bradley SLC 500 control installations. Although it does not directly control machinery, it supports the engineering and maintenance activities required to keep a controller-based system operating.

PLC Commissioning

During initial commissioning, the programming cable connects a compatible computer to the SLC processor. Engineers can use supported software to configure the controller, transfer programs, and verify basic system operation.

The cable helps provide access to the controller without requiring changes to the main control-panel wiring.

Program Maintenance

Industrial control programs may need to be updated when production requirements change or when equipment is modified. The 1747-CP3 supports serial access for compatible programming operations.

Before transferring a program, maintenance personnel should verify the controller model, firmware, project file, and communication settings. Existing programs should be backed up before making changes.

Troubleshooting and Diagnostics

When a machine stops unexpectedly or a controller communication issue occurs, technicians may need to connect a programming computer to inspect the PLC.

The cable can support this process by providing access to the processor’s RS-232 port. It is a useful maintenance accessory for facilities that continue operating legacy SLC 500 equipment.

Legacy System Support

Many industrial facilities maintain control systems long after the original equipment has been discontinued. The 1747-CP3 remains relevant in these environments because it supports programming and communication tasks associated with compatible SLC processors.

Maintaining suitable programming accessories can help reduce delays during troubleshooting and planned maintenance.

Industrial Applications

The 1747-CP3 is primarily used in industrial automation environments where Allen-Bradley SLC 500 controllers remain installed.

1. Manufacturing Production Lines

Manufacturing equipment often relies on SLC processors to coordinate motors, sensors, actuators, and machine sequences.

The programming cable allows engineers to connect to compatible controllers for program maintenance, diagnostics, and commissioning activities.

2. Packaging Machinery

Packaging machines may use SLC 500 controllers to manage product feeding, conveyor movement, counting, and sequencing.

The 1747-CP3 can support maintenance personnel who need to access the controller program or investigate machine operation through the supported serial interface.

3. Material Handling Systems

Conveyors, transfer equipment, and sorting machinery may contain legacy SLC controllers.

During troubleshooting, the cable can provide a direct programming connection to a compatible processor, helping technicians inspect controller status and investigate control logic.

4. Industrial Process Equipment

Some process installations continue to use SLC 500 controllers for auxiliary equipment, pumps, valves, and other automated functions.

The 1747-CP3 can be used during scheduled maintenance and system diagnostics where the processor supports the required RS-232 connection.

5. Electrical and Control Panel Maintenance

Industrial control panels require periodic inspection, program backup, and configuration checks. A dedicated programming cable helps maintenance teams connect to supported PLC hardware without modifying the existing control architecture.

6. Legacy Automation Upgrades

When an existing SLC 500 installation is being evaluated for modernization, technicians may need to retrieve program information and inspect the controller configuration.

The 1747-CP3 can support access to compatible processors during the assessment and preparation stages of an upgrade project.

Installation and System Integration

Correct connection and configuration are essential for reliable communication between the programming computer and the PLC.

1. Verify Controller Compatibility

Before connecting the cable, identify the exact SLC processor model and locate its RS-232 communication port.

The 1747-CP3 is associated with SLC 5/03, 5/04, and 5/05 processors. Do not assume that every SLC 500 processor uses the same communication port or cable arrangement.

2. Inspect the Connectors

Check both 9-pin female D-shell connectors for bent contacts, corrosion, contamination, or mechanical damage.

The right-angle connector should be positioned so that it does not place excessive stress on the controller port. The straight connector should be secured properly at the computer or DTE end.

3. Connect the Cable Correctly

Connect the appropriate end to the controller’s RS-232 channel and the other end to the supported DTE device.

Do not force a connector into place. Confirm the connector orientation and secure the retaining screws where applicable.

4. Configure the Programming Software

After establishing the physical connection, select the correct serial communication interface and settings in the supported programming software.

The communication parameters must match the controller configuration. These may include baud rate, parity, data bits, stop bits, and other applicable settings.

5. Confirm Communication

Once the cable is connected and the software is configured, attempt to establish communication with the controller.

If communication fails, check:

• The selected computer serial port.
• The controller’s RS-232 port.
• The cable connector seating.
• The communication settings.
• The cable’s internal wiring compatibility.
• The controller’s operating condition.
• The programming software and driver configuration.

6. Protect the Cable During Use

Avoid sharp bends, excessive pulling, crushing, and repeated stress at the connector housings.

Keep the cable away from high-temperature surfaces and areas where moving machinery could damage it. Store it in a clean, dry location when not in use.

Compatible System Components

The 1747-CP3 operates as part of a programming and maintenance setup. The following components are commonly associated with its intended application.

The cable is a communication accessory and does not replace the PLC processor, programming software, or any required computer interface hardware.

Alternative Models and Replacement Considerations

When replacing the 1747-CP3, the most important factors are connector type, internal wiring, communication interface, and supported controller model.

Before purchasing a replacement, compare:

• The complete catalog number.
• Cable length.
• Connector gender and orientation.
• RS-232 pin assignments.
• Internal jumper arrangement.
• Supported SLC processor models.
• Computer serial-interface requirements.
• Product condition and testing status.

A USB adapter or replacement cable should not be assumed to provide the same functionality simply because it is advertised as compatible with the 1747-CP3.

Key Advantages

Dedicated SLC 500 Programming Connection

The cable is designed for supported SLC 500 processor communication, providing a dedicated connection for programming and maintenance tasks.

Standard RS-232 Interface

Its RS-232 interface supports serial communication with compatible computers and DTE devices.

10-Foot Cable Length

The approximately 10-foot cable provides practical working distance between the control cabinet and a nearby programming computer.

Specialized Connector Arrangement

The right-angle and straight 9-pin D-shell connectors accommodate the intended connection layout.

Support for Legacy Equipment

The cable remains useful for facilities maintaining SLC 5/03, 5/04, and 5/05 installations.

Useful for Maintenance and Diagnostics

It supports controller access for program transfer, configuration, and troubleshooting when used with compatible hardware and software.

Simple Physical Connection

The cable provides a direct serial link without requiring a separate network communication module for the intended RS-232 connection.

Technical FAQs

1. What is the Allen-Bradley 1747-CP3?

The 1747-CP3 is an RS-232 programmer cable designed for connecting compatible Allen-Bradley SLC 500 processors to a computer or other DTE device.

2. How long is the 1747-CP3 cable?

The nominal cable length is 10 feet, approximately 3 meters.

3. Which PLC models are compatible with the 1747-CP3?

It is associated with SLC 5/03, SLC 5/04, and SLC 5/05 processors. Always confirm the exact processor port and communication requirements before use.

4. What communication interface does it use?

The cable uses RS-232 serial communication.

5. What type of connectors does it have?

It uses two 9-pin female D-shell connectors. One is right-angle and the other is straight.

6. Can the 1747-CP3 connect a PLC to a computer?

Yes. It is designed to connect a compatible SLC processor’s RS-232 communication channel to a computer or other supported DTE device.

7. Can I use an ordinary DB9 serial cable instead?

Not necessarily. The 1747-CP3 has a specific internal wiring and jumper arrangement. A standard serial cable may have a different pinout and may not establish communication.

8. Is the 1747-CP3 still manufactured?

No. Rockwell Automation announced its discontinuation effective September 30, 2024. Availability may depend on remaining inventory and the industrial spare-parts market.

9. Can I use a USB-to-serial adapter with this cable?

A compatible USB-to-RS-232 adapter may be used when the computer does not have a native serial port. Confirm the adapter’s driver support, electrical compatibility, and serial-port configuration.

10. Does the supplied 3 kg weight represent the cable itself?

No. The 3 kg figure supplied for this product is identified as shipping weight. The actual cable is substantially lighter, and the final shipping weight may include packaging or other shipment materials.

Procurement and Maintenance Recommendations

The 1747-CP3 is a discontinued programming accessory, so buyers should verify the complete catalog number and product condition before ordering.

For new-old-stock or used units, request clear photographs of both connectors, the cable jacket, and any available product identification. Check for damaged pins, loose connector housings, cracked insulation, and signs of previous repairs.

For replacement applications, confirm the cable length, RS-232 wiring arrangement, connector orientation, and supported processor model. A cable that looks similar may not provide the correct electrical connection.

During maintenance, avoid pulling the cable by its connectors or bending it sharply near the connector housings. Store it away from moisture, excessive heat, and mechanical damage. If communication becomes intermittent, inspect the connectors and test the cable before assuming that the PLC processor is faulty.

For facilities maintaining legacy SLC 500 systems, keeping a verified programming cable available can help reduce troubleshooting delays and support planned controller maintenance.

Conclusion

The Allen-Bradley 1747-CP3 Programmer Cable is a dedicated RS-232 communication accessory for supported SLC 500 controllers. With a nominal length of 10 feet and two 9-pin female D-shell connectors, it provides a physical connection between compatible PLC processors and programming computers.

Its primary uses include controller programming, configuration, program transfer, monitoring, and troubleshooting. Since the product has been discontinued, accurate identification and careful verification of connector wiring are important when sourcing a replacement.

For industrial facilities operating legacy Allen-Bradley SLC 500 equipment, the 1747-CP3 remains a relevant maintenance accessory for supported serial programming connections.