Product Overview
The Allen-Bradley 1785-L46C15 is a ControlNet PLC-5 processor with protected memory, designed for demanding industrial automation applications. As part of the PLC-5 family, this processor provides reliable control for field devices, handling both discrete and analog I/O with ease. With a 48-kiloword user memory and support for up to 125 I/O chassis, the 1785-L46C15 is a robust choice for mid-to-large-scale control systems.
Key Technical Specifications
| Specification |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1785-L46C15 |
| Module Type |
ControlNet PLC-5 Processor with Protected Memory |
| Processor |
PLC-5/46C |
| Max User Memory Words |
48 Kilowords |
| Battery-Backed Static RAM |
Yes |
| EEPROM Program Backup Option |
Yes (using 1785-ME16, -ME32, -ME64, and -M100) |
| Protected Memory |
Yes |
| Max Total I/O |
Forcible 2048 (any mix) or 2048 in + 2048 out (complementary), Nonforcible 48000 |
| Max Analog I/O |
Forcible 2048 and Nonforcible 48000 |
| I/O Scan Time Per Rack |
ControlNet I/O 0.5 ms (average); Universal Remote I/O 10 ms at 57.6 kbits/s, 7 ms at 115.2 kbits/s, 3 ms at 230.4 mbits/s |
| Max I/O Chassis Total |
125 |
| Max I/O Chassis Extended Local |
0 |
| Max I/O Chassis Universal Remote |
60 |
| RS-232-C/422-A/423-A Ports |
1 |
| Control Coprocessor Expansion Port |
Yes |
Performance and Memory
The 1785-L46C15 provides 48 kilowords of user memory, with a limit of 32K words per data-table file. This generous memory allocation supports complex control programs and large data tables. The processor includes battery-backed static RAM for program retention, and it offers an EEPROM backup option using compatible memory modules (1785-ME16, -ME32, -ME64, -M100). Protected memory ensures that critical data remains secure from unauthorized changes.
I/O and Communication Capabilities
With a maximum of 2048 forcible I/O points (or 2048 in + 2048 out in complementary mode) and 48000 nonforcible I/O points, the 1785-L46C15 handles substantial field wiring. The ControlNet port runs at 5 Mbit/s and supports up to 99 nodes per link with repeaters. Additionally, the remote I/O and DH+ ports operate at speeds from 57.6 kbit/s to 230.4 kbit/s, with scan times as low as 3 ms per rack. The processor supports up to 125 total I/O chassis, with 60 universal remote chassis, making it suitable for distributed architectures.
Industrial Applications
This processor excels in applications requiring high-speed control and extensive I/O, such as assembly lines, material handling, and process control. Its ControlNet redundancy capability (when paired with the 1785-CHBM Hot Backup Cartridge) ensures minimal downtime in critical processes. The 1785-L46C15 also integrates with a wide range of I/O modules, including 1771, 1794, 1746, and 1791 series, providing flexibility in system design.
Installation and Setup
Mount the 1785-L46C15 in a 1771 I/O chassis, ensuring proper keying via pins 40, 42, 54, and 56. The processor supports ½-slot, single-slot, and double-slot addressing, so configure the chassis backplane accordingly. Connect the ControlNet network via the base-configured port, and use the front panel 3-pin ports for DH+ or remote I/O communications. The RS-232-C/422-A/423-A port allows for programming and diagnostic connections. Ensure adequate airflow for cooling, as the module dissipates up to 59 BTU/hour.
Maintenance and Reliability
Regularly inspect the battery-backed RAM to ensure program retention; replace the battery as recommended by the manufacturer. Operate the processor within its specified environmental range (0-60°C, 5-95% non-condensing humidity) to maintain reliability. The unit withstands 30G operational shock and 1G vibration at 10-500Hz, making it suitable for harsh industrial environments. With proper care, this processor provides long service life and minimal downtime.
Compatibility and Integration
The Allen-Bradley 1785-L46C15 integrates seamlessly with ControlNet networks and supports remote I/O and DH+ protocols. It is compatible with a broad range of Allen-Bradley I/O modules and can be used in systems with 1771, 1794, 1746, and 1791 series modules. The Control Coprocessor Expansion Port allows for additional functionality, such as custom communication or processing tasks.
Selection and Purchasing Advice
Before purchasing, verify that the 1785-L46C15 meets your system's memory and I/O requirements. Consider the need for the ControlNet Hot Backup Cartridge (1785-CHBM) if redundancy is essential. Ensure you have the correct memory modules for backup if using EEPROM. PLC Source PRO offers this module with fast shipping and reliable customer support, ensuring you get the right part for your automation needs.