Allen-Bradley 1785-L80C15 ControlNet PLC5 Processor

Allen-Bradley 1785-L40C15 PLC-5 ControlNet Processor

Product Introduction

The 1785-L40C15 processor belongs to the esteemed Allen-Bradley PLC-5 family, and it specifically targets ControlNet-based automation systems. This controller delivers a robust combination of processing power, extensive memory, and versatile networking capabilities. Its most notable feature is the integration of two (2) ControlNet communication ports, which enable redundant media schemes and support high-speed hot backup configurations using the 1785-CBHM cartridge.

Furthermore, the 1785-L40C15 excels at managing distributed I/O architectures. It communicates seamlessly with Bulletin 1771, 1794, 1746, and 1791 I/O modules, including 8-point, 16-point, 32-point, and intelligent specialty modules. Meanwhile, its comprehensive embedded communication suite—including Data Highway Plus (DH+), Remote I/O (RIO), and serial ports—ensures smooth integration with both legacy equipment and modern supervisory systems. This makes the 1785-L40C15 a versatile and dependable choice for engineers upgrading or expanding their control infrastructure.

Technical Specifications

Memory and I/O Capacity
The 1785-L40C15 provides a maximum user memory of 48K Words of battery-backed static RAM. For discrete I/O, it handles a total of 2048 points in any mix, or 2048 inputs and 2048 outputs in complementary mode. To reach its full memory potential, users can install optional modules such as the 1785-ME32, 1785-ME64, and 1785-M100. For analog applications, the controller supports up to 2048 forcible and 48,000 non-forcible analog I/O points.

Communication Ports
This controller boasts a rich array of embedded communication options. It includes a serial port (RS-232-C/422-A/423-A) supporting DF1 and ASCII protocols for programming and point-to-point communication. Additionally, it features Data Highway Plus (DH+), Remote I/O (RIO), and a DH port that utilizes the 1785-KA adapter. Most significantly, the 1785-L40C15 includes two (2) ControlNet ports, which are essential for high-speed networked control and redundant processor configurations.

Processing Speed and Scan Time
The processor delivers a program scan time of just 0.5 ms per K-word for bit logic and 2 ms per K-word for typical instructions. This rapid execution ensures timely response to input changes, which is critical for time-sensitive processes. For I/O scanning, ControlNet racks average 0.5 ms per rack, while Universal Remote I/O scan times vary from 3 ms to 10 ms depending on baud rate (230.4 kbits/s, 115.2 kbits/s, or 57.6 kbits/s).

Hardware and Addressing
The 1785-L40C15 mounts in the left-most slot of a 1771-A1B, -A2B, -A3B, -A3B1, or -A4B chassis. It offers flexible hardware addressing with 2-slot, 1-slot, and 1/2-slot configurations. This flexibility allows system designers to optimize chassis utilization based on specific application needs. Moreover, the controller includes a Control Coprocessor Expansion Port for future enhancements.

Redundancy and Data Retention
The 1785-L40C15 supports a hot backup system through the 1785-CBHM ControlNet Hot Backup Cartridge. This cartridge resides in each ControlNet processor rack, enabling high-speed processor switchover and synchronized data transfer. To retain program and data during power loss, the controller uses a 1770-XYC battery. Users should only replace this battery while the processor remains powered on to prevent data loss.

Mechanical and Environmental Parameters

The 1785-L40C15 withstands demanding industrial environments with ease. It operates reliably within a temperature range of 0 to 60°C (32 to 140°F) and tolerates relative humidity from 5% to 95% (non-condensing). The module draws approximately 3.2 Amps from the 5V DC backplane and 0.7 Amps from the 24V DC supply. Its rugged construction ensures stable performance even in settings with moderate shock and vibration, consistent with the high-quality standards of Allen-Bradley.

Installation and Mounting Guide

A qualified automation technician should carry out the installation of the 1785-L40C15. First, ensure the selected 1771 chassis is properly mounted, grounded, and powered off. Then, insert the processor into the left-most slot of the chassis, applying firm and even pressure to seat it correctly into the backplane connectors.

Next, configure the addressing switches (S1, S2, S3) to define the node address for DH+ and RIO networks. Afterward, connect the required communication cables to the appropriate ports. For ControlNet, use the two BNC or coax connectors on the front face. Finally, apply power to the chassis and observe the status LEDs to confirm a successful initialization. Always handle the module with proper ESD precautions.

Packaging and Shipping Information

Each 1785-L40C15 processor comes in secure packaging to ensure safe transit. The package contains the processor module itself, along with a static-sensitive device warning label and a basic installation guide.

Shipping Methods:
All orders move through trusted global couriers for fast and reliable delivery.

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Frequently Asked Questions (FAQ)

Q1: What is the maximum user memory of the 1785-L40C15 controller?
A: The 1785-L40C15 provides a maximum user memory of 48 Kilowords (48K Words).

Q2: Can the 1785-L40C15 work in a redundant control system?
A: Yes, this PLC-5 processor supports redundancy via the 1785-CBHM hot backup cartridge, and it uses its dual ControlNet ports for high-speed data synchronization.

Q3: What battery does the 1785-L40C15 use, and when should users replace it?
A: It uses the 1770-XYC battery. Users must perform replacement while the processor remains powered on to avoid losing the contents of the static RAM.

Q4: Is the 1785-L40C15 compatible with 1746 I/O modules?
A: Yes, this Allen-Bradley controller supports a wide range of distributed I/O platforms, including Bulletin 1746, 1771, 1794, and 1791 I/O families.

Q5: How many ControlNet ports does the 1785-L40C15 have, and what purpose do they serve?
A: The 1785-L40C15 features two (2) ControlNet ports, which support high-speed networking and enable hot backup configurations.