Allen-Bradley 1785-L60L PLC-5/60L Processor for Industrial Control

Product Introduction

When your control system demands a reliable central processor that can manage extensive I/O and multiple communication networks, the Allen-Bradley 1785-L60L delivers. As a member of the PLC-5 controller series from Rockwell Automation, this programmable controller functions as the backbone of any automation system based on the Allen-Bradley PLC-5 family. The 1785-L60L interconnects local, extended, and remote I/O modules across different communication interfaces, making it a versatile choice for complex industrial environments.

Technical Specifications Breakdown

Understanding the key specifications of the 1785-L60L helps you evaluate its fit for your application. The processor offers a maximum user memory of 64 Kilowords, providing ample space for control programs and data tables. It supports a maximum total I/O of 3072 points, which can be any mix of inputs and outputs, or 3072 inputs plus 3072 outputs in complementary mode. This flexibility allows you to configure the system exactly as needed.

The I/O scan time per rack varies by link type: 0.5 ms for extended local I/O, and for remote I/O links, 10 ms at 57.6 kbits/s, 7 ms at 115.2 kbits/s, and 3 ms at 230.4 mbits/s. This ensures fast and deterministic data exchange. The controller can handle up to 81 total I/O chassis, with a maximum of 16 extended local chassis and 32 universal remote chassis per I/O link. The backplane load is 3.3 Amps at 5 Volts, which is important for power supply planning.

Industry Applications

The 1785-L60L excels in applications requiring centralized control of distributed I/O. For example, in a manufacturing plant with multiple assembly lines, the processor can manage local I/O for one line while using remote I/O links to control others up to 3048 meters away (at 57.6 kbits/s). Its three communication channels—Channel 1A, 1B, and 2—allow simultaneous operation as a remote I/O scanner, DH+ peer-to-peer network node, and extended local I/O controller. This makes it ideal for automotive, food and beverage, and material handling systems where coordination across large areas is critical.

Another common use is in process industries where the controller must interface with both analog and discrete I/O. With support for up to 3072 analog I/O points, the 1785-L60L can handle temperature, pressure, and flow measurements while also managing discrete actuators and sensors. The battery-backed static RAM ensures program retention during power outages, and the EEPROM backup option (using 1785-ME16, -ME32, -ME64, or -M100 modules) provides additional security for critical applications.

Compatibility & Integration

The 1785-L60L integrates seamlessly with other Allen-Bradley PLC-5 components. It features one RS-232-C/422-A/423-A port (Channel 0) for ASCII and DF1 protocol communication, and a control coprocessor expansion port for additional functionality. Channels 1A and 1B can be configured as remote I/O scanners, remote I/O adapters, or DH+ communication interfaces, enabling peer-to-peer networking with other PLC-5 controllers or higher-level systems. The extended local I/O port (Channel 2) connects to a 1771-ALX adapter for high-speed I/O expansion up to 100 feet.

For programming, you can use a DH+ link or the Channel 0 serial port. The three-position key-switch on the front panel allows easy mode selection: RUN, PROGRAM, or REMOTE, with sub-modes for testing and editing. This flexibility simplifies commissioning and maintenance.

Selection Guide & Purchasing Advice

Before purchasing the 1785-L60L, verify your system requirements. Ensure your power supply can deliver 3.3 Amps at 5 Volts on the backplane. Choose the appropriate memory module (1785-ME16, -ME32, -ME64, or -M100) if you need EEPROM backup. Confirm the communication distances: for DH+ links, cable length ranges from 3048 m at 57.6 kbits/s to 762 m at 230.4 kbits/s. All devices on a DH+ link must use the same transmission rate.

For current availability and lifecycle status, contact BluePLC Industrial. Our team can help you verify stock, recommend compatible accessories, and provide support for your automation project. The 1785-L60L remains a robust choice for PLC-5 systems, offering proven reliability and extensive I/O capabilities.