Product Overview
The Allen-Bradley 1785-L40C is a ControlNet processor module from the PLC-5 series, designed for controlling field device inputs and outputs in industrial automation systems. This module provides 48K words of battery-backed SRAM and supports up to 2048 total I/O points, offering a cost-effective solution for medium to large-scale control applications. Its integrated ControlNet network capability reduces wiring costs and improves system reliability compared to traditional point-to-point connections.
Technical Specifications Breakdown
Key parameters for the 1785-L40C are listed below for quick reference:
| Feature | Specification |
|---|---|
| Module Type | ControlNet Processor Module |
| Processor | PLC-5/40 |
| Max User Memory Words | 48 Kilowords |
| Battery-Backed Static RAM | Yes |
| Max Total I/O | 2048 (any mix) or 2048 in + 2048 out (complementary) |
| Max Analog I/O | 2048 |
| RS-232-C/422-A/423-A Ports | 1 |
| Control Coprocessor Expansion Port | Yes |
| Backplane Current at 5V DC | 3.3A |
| Maximum Heat Dissipation | 59 BTU/hour |
| Operating Temperature | 0-60 °C (32-140 °F) |
| Storage Temperature | –40-85 °C (–40-185 °F) |
| Relative Humidity | 5-95% noncondensing |
| Operational Shock | 30G |
| Vibration | 1G at 10-500Hz |
| Weight | 1.42kg (3lbs) |
| Certifications | UL, CE, CSA, C-TICK |
Industry Applications
This controller is well-suited for manufacturing lines where ControlNet networking reduces installation and maintenance costs. In automotive assembly, its 2048 I/O capacity handles multiple robotic workcells without additional processors. For material handling systems, the 48K word memory supports complex sequencing logic, minimizing downtime and operational expenses. The module's 5 Mbps ControlNet transmission rate enables fast data exchange, improving throughput in high-speed packaging applications.
Installation & Setup Guidance
Mount the 1785-L40C in a 1771 I/O chassis slot. Connect the ControlNet network via the base-configured RJ45 connector. Use the 8-pin mini-DIN connector for programming and the 25-pin D-shell serial port for configuration. Set the serial port transmission rate between 57.6 kbits/s and 230.4 kbits/s as needed. The I/O scan time per rack varies from 10 ms at 57.6 kbits/s to 3 ms at 230.4 kbits/s. Ensure the backplane current draw of 3.3A at 5V DC is within the chassis power supply capacity.
Maintenance & Reliability
Periodically inspect the battery-backed SRAM to ensure program retention during power loss. The module operates reliably at 0-60 °C and 5-95% noncondensing humidity. Its 30G shock and 1G vibration tolerance suit demanding industrial environments. Verify the open-style enclosure is installed in a clean, dry location to prevent contamination.
Compatibility & Integration
The 1785-L40C supports 1771, 1794, 1746, and 1791 I/O modules, including 8-point, 16-point, 32-point, and intelligent I/O types. It integrates with ControlNet networks and includes a DH+ port for legacy connectivity. The Control Coprocessor Expansion Port allows additional processing capabilities. For hot backup systems, the 1785-CHBM cartridge is supported.
Selection Guide & Purchasing Advice
When selecting a processor, evaluate your I/O count and memory needs. The 1785-L40C offers 48K words and 2048 I/O, balancing cost and capacity for mid-range applications. Please verify current lifecycle status and availability with AutoDCSTech before ordering.
Troubleshooting & Common Issues
If the module fails to communicate, check the ControlNet cable and connector integrity. Verify the serial port settings match the programming device. For memory errors, replace the battery and reload the program. Monitor the backplane current draw to avoid power supply overload.
Availability & Condition at AutoDCSTech
| Part Number | 1785-L40C |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
