Product Overview

The 1785-L60L is a standard processor from the Allen-Bradley PLC-5 series. It serves as the central controller in a control system. This unit connects local, extended, and remote I/O modules. It uses three integrated communication interfaces. Channel 1A and 1B work as remote I/O scanners, adapters, or DH+ links. Channel 2 is an extended-local I/O port. The front panel has a 25-pin RS-232C port (Channel 0) for ASCII and DF1 protocols. An 8-pin mini DIN connector provides a DH+ programming terminal. The processor supports up to 3072 total I/O points. It operates in Program, Run, and Remote modes. A three-position key switch selects the mode. The memory size is 64 kilowords. Battery-backed static RAM retains the program. EEPROM modules (1785-ME16, -ME32, -ME64, -M100) can be used for backup. The backplane load is 3.3 Amps at 5 Volts.

Application Scenarios

This controller fits many industrial automation tasks. It works in manufacturing lines, material handling, and process control. Use it for machine control with high I/O counts. The remote I/O scanner mode lets it supervise other controllers. The DH+ link enables peer-to-peer networking with other PLC-5 units. Extended local I/O is ideal when speed matters over distance. The processor can manage up to 81 I/O chassis. It supports 32 chassis per remote I/O link. The extended local link handles up to 16 chassis. Typical applications include assembly lines, packaging, and water treatment plants.

Technical Specifications

• Processor Type: PLC-5/60L
• Max User Memory: 64 Kilowords
• Max Total I/O: 3072 (any mix) or 3072 in + 3072 out (complementary)
• Max Analog I/O: 3072
• I/O Scan Time Per Rack: 0.5 ms (ext. local), up to 10 ms at 57.6 kbps
• Communication Ports: Channel 0 (RS-232C), Channel 1A/1B (RIO/DH+), Channel 2 (ext. local I/O)
• Protocol Support: ASCII, DF1 full-duplex/half-duplex, DH+, remote I/O scanner/adapter
• Battery-Backed Static RAM: Yes
• EEPROM Backup Option: Yes (using 1785-MExx modules)
• Protected Memory: No
• Max I/O Chassis Total: 81
• Max I/O Chassis Extended Local: 16
• Max I/O Chassis Universal Remote: 32
• Backplane Current: 3.3 A at 5 VDC
• Indicators: BATT, PROC, FORCE, COMM, Channel status LEDs

Installation & Maintenance Guide

Install the 1785-L60L in a 1771 I/O chassis. Ensure the backplane power is off before insertion. Connect the power supply (e.g., 1771-P4S). Set the key switch to PROG mode. Wire the communication cables properly. For extended local I/O, use the 1771-ALX adapter. Limit the cable length to 100 feet. For remote I/O, follow the cable length guidelines. DH+ cable length depends on speed: 3048 m at 57.6 kbps, 762 m at 230.4 kbps. Check the battery status indicator. Replace the battery if the BATT LED is red. Use only approved memory modules. Clean the front panel with a dry cloth. Avoid exposure to dust and moisture. For firmware updates, use the DH+ link or Channel 0.

Packing List

1x Allen-Bradley 1785-L60L processor
1x Battery (installed)
1x Key switch (attached)
1x User manual (digital CD)
No additional accessories.