Allen-Bradley 1769-L31 CompactLogix Controller 512KB

Allen-Bradley 1769-L31 CompactLogix Controller – Product Introduction

The Allen-Bradley 1769-L31 is a Programmable Automation Controller from the 1769 CompactLogix family. Specifically, this controller is designed for small to medium-scale applications where serial communication remains essential. It features 512 KB of user memory and two RS232 communication ports, providing flexible connectivity for legacy and modern systems.

Additionally, the 1769-L31 supports up to 16 local I/O modules and can be expanded across three I/O banks. This scalability makes it suitable for growing automation needs. The controller uses a 1747-BA battery to retain user programs and data during power loss, with a dedicated BAT LED for status monitoring.

Communication Ports and Protocols

The 1769-L31 stands out with its dual RS232 serial interfaces. Channel 0 is fully isolated and supports DF1, DH-485, and ASCII protocols. Channel 1 is non-isolated and supports DF1 and DH-485 protocols. Both ports achieve transmission speeds up to 38.4 kbps.

For programming and connectivity, use the 1747-CP3 or 1756-CP3 serial cables. The 1769-L31 also supports non-volatile memory expansion via the 1784-CF64 or 1784-CF128 CompactFlash cards. This feature allows convenient program backup and data logging.

Memory and Processing Capabilities

The 1769-L31 provides 512 KB of user memory, sufficient for moderate-sized control programs. It supports up to four tasks, enabling structured programming for different process requirements. The controller draws 330 mA at 5V DC and 40 mA at 24V DC, with a maximum power dissipation of 4.5 W.

Furthermore, the 1769-L31 includes I/O forcing capabilities, which expedite system commissioning and troubleshooting. This feature allows engineers to override input and output states during testing without modifying the application code.

I/O Expansion and System Configuration

This controller supports a maximum of 16 local 1769 Compact I/O modules. Additionally, it allows expansion up to three I/O banks, providing flexibility for system growth. However, the 1769-L31 must be installed as the leftmost module in the chassis. It also requires placement within four modules of the system power supply, as specified by its power supply distance rating.

For installation, the 1769-L31 supports both DIN-rail and panel mounting methods. It uses an open-style enclosure and operates within a temperature range of 0 to 60 °C (32 to 140 °F). The module measures approximately 8 x 8 x 5 inches and weighs 2 lbs.

LED Status Indicators

The 1769-L31 features easily identifiable LED indicators for rapid diagnostics. These include:

• RUN – Indicates the controller is executing the user program

• FORCE – Shows that I/O forcing is active

• BAT – Alerts when the battery voltage is low

• OK – Confirms the controller is operating normally

• I/O – Displays I/O module status

• DHCO – Indicates DH-485 communication activity

• Channel 0 and Channel 1 – Show serial port activity

Each LED operates independently, providing clear and immediate status feedback to operators and maintenance personnel.

Installation and Mounting Guidelines

Installing the 1769-L31 requires careful planning. Always place it as the leftmost module in the CompactLogix system. Additionally, ensure it is within four module positions of the power supply to comply with the power supply distance rating. Use copper wire rated for 90 °C, with solid wire sizes from 22 to 14 AWG or stranded wire from 22 to 16 AWG.

For vibration resistance, the 1769-L31 withstands 5G from 10 to 500 Hz with 0.030-inch peak-to-peak displacement. It also tolerates operating shock of 30 g. The controller is rated for overvoltage category II industrial standards, making it suitable for demanding environments.

Packaging List

• Allen-Bradley 1769-L31 CompactLogix Controller (1 unit)

• 1747-BA battery (pre-installed)

• Removable terminal block

• Mounting hardware kit (DIN rail clips and panel brackets)

• Quick Start Guide (printed)

Note: The controller is shipped in anti-static packaging to prevent electrostatic damage during transit.

Shipping Information

All orders are dispatched via FedEx, UPS, or DHL with full tracking capabilities. Express and economy shipping options are available upon request.

Frequently Asked Questions (FAQ)

Q1: What is the user memory capacity of the 1769-L31?
A: The 1769-L31 provides 512 KB of user memory for program logic and data storage. For additional non-volatile storage, use the 1784-CF64 or 1784-CF128 CompactFlash card.

Q2: What protocols does the dual RS232 ports support?
A: Channel 0 on the 1769-L31 supports DF1, DH-485, and ASCII. Channel 1 supports DF1 and DH-485. Both ports operate at speeds up to 38.4 kbps.

Q3: How many I/O modules can I connect to this controller?
A: The 1769-L31 supports up to 16 local I/O modules and can be expanded across up to three I/O banks, providing excellent scalability.

Q4: Does this controller come with a battery included?
A: Yes. The 1769-L31 ships with a 1747-BA battery pre-installed to maintain user memory during power outages. A BAT status LED alerts you when replacement is needed.

Q5: Can the 1769-L31 be used with Ethernet networks?
A: No. The 1769-L31 is a serial-only controller with dual RS232 ports. For Ethernet connectivity, consider other CompactLogix models like the 1769-L30ERM or 1769-L33ERM.