Allen-Bradley 1785-L40C15 PLC-5/40 ControlNet Processor | Replacement, Equivalent & Selection Guide
The Allen-Bradley 1785-L40C15 is a high-performance PLC-5/40 processor with integrated ControlNet communication, designed for demanding industrial automation environments. This page provides full technical specifications, compatible replacement models, application guidance, and sourcing information to help engineers and procurement teams make confident decisions.
Technical Specifications
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Part Number | 1785-L40C15 |
| Series | PLC-5/40 |
| Communication | ControlNet (built-in) |
| User Memory | 48K words |
| I/O Capacity | Up to 3,072 I/O points |
| Data Table Size | Up to 32,767 elements |
| Scan Time | ~1 ms/K (typical) |
| Power Supply | Backplane powered (1771 chassis) |
| Operating Temperature | 0°C to 60°C |
| Weight | 1,420 g (approx.) |
| Form Factor | Single-slot, 1771 chassis compatible |
| Programming Software | RSLogix 5 / PLC-5 Programming Terminal |
Compatible Replacement & Equivalent Models
The following models are commonly evaluated as direct or functional replacements for the 1785-L40C15. Always verify firmware, I/O capacity, and network compatibility before substitution.
| Part Number | Series | Memory | Communication | Notes |
|---|---|---|---|---|
| 1785-L40B | PLC-5/40 | 48K words | DH+/RIO | Same processor class; no ControlNet |
| 1785-L60C15 | PLC-5/60 | 100K words | ControlNet | Larger memory upgrade path |
| 1785-L80C15 | PLC-5/80 | 100K words | ControlNet | Maximum PLC-5 capacity |
| 1756-L71 (ControlLogix) | ControlLogix | 2MB | EtherNet/IP, ControlNet | Modern migration target; requires re-engineering |
| 1756-L73 (ControlLogix) | ControlLogix | 8MB | EtherNet/IP, ControlNet | High-capacity migration option |
Note: PLC-5 to ControlLogix migration requires program conversion using Rockwell’s Migration Toolkit. Konmask can assist with sourcing both legacy and migration hardware.
Why Choose the Original Model
- Drop-in compatibility: Fits existing 1771 chassis without hardware modification.
- Proven reliability: Decades of field-proven performance in process and discrete manufacturing.
- ControlNet integration: Native deterministic ControlNet port eliminates the need for a separate communication module.
- Minimal downtime: Replacement with the same part number requires no program changes or I/O remapping.
- Cost-effective maintenance: Extending PLC-5 system life defers costly migration projects.
Typical Applications
- Automotive assembly lines with ControlNet-based I/O networks
- Oil & gas process control systems using 1771 remote I/O
- Water/wastewater treatment plant SCADA integration
- Food & beverage packaging lines requiring deterministic scan times
- Power generation and utilities with legacy PLC-5 infrastructure
- Mining and materials handling conveyor control systems
System Compatibility
- Chassis: Allen-Bradley 1771 I/O chassis (all sizes)
- Power Supplies: 1771-P4S, 1771-P6S, 1771-P7 series
- Programming: RSLogix 5 (v8.x and above recommended), 6200 Series Software
- Communication Modules: Compatible with 1771-ACN15 (ControlNet adapter), 1771-ACNR15 (redundant)
- HMI: PanelView 550/900/1000/1400 via ControlNet or DH+
- SCADA: FactoryTalk View, Wonderware, Ignition (via OPC-DA/UA gateway)
Selection Guide
Use the criteria below to determine whether the 1785-L40C15 is the right choice or whether an alternative should be considered:
| Requirement | Recommended Model |
|---|---|
| Direct replacement, same chassis, ControlNet required | 1785-L40C15 ✓ |
| Same chassis, no ControlNet needed | 1785-L40B |
| Need more memory, keep ControlNet, same chassis | 1785-L60C15 |
| Long-term migration to modern platform | 1756-L71 / 1756-L73 (ControlLogix) |
| Budget-constrained, refurbished acceptable | 1785-L40C15 (refurbished) — available at Konmask |
Quality Assurance & Sourcing
- Source: Konmask.com sources 1785-L40C15 units from authorized distributors and verified secondary market suppliers.
- Testing: All refurbished units undergo functional power-on testing and visual inspection prior to shipment.
- Warranty: 90-day replacement warranty on all stocked units (terms apply).
- Authenticity: Counterfeit screening performed on all incoming inventory; certificates of conformance available on request.
- Lead Time: In-stock units ship within 1–3 business days; sourced units typically 5–10 business days.
How to Order
- Confirm your part number: 1785-L40C15 (check the label on your existing module).
- Specify condition preference: New, Refurbished, or Surplus.
- Add to cart or contact us directly for bulk/project pricing.
- Provide your shipping address and preferred freight method at checkout.
- For urgent requirements, email support@konmask.com or call +0086 19859288691 for expedited sourcing.
Replacement & Compatibility FAQ
Q: Can I replace a 1785-L40C15 with a 1785-L40B without any changes?
A: The 1785-L40B fits the same chassis slot but lacks the ControlNet port. If your system uses ControlNet I/O or peer communication, you will need to add a separate ControlNet scanner module (e.g., 1771-ACN15) or choose a ControlNet-equipped processor.
Q: Is the 1785-L40C15 still manufactured by Rockwell Automation?
A: The PLC-5 series has been discontinued by Rockwell Automation. Konmask specializes in sourcing new-old-stock and quality-tested refurbished units to support ongoing maintenance needs.
Q: Can I migrate my PLC-5/40 program to ControlLogix directly?
A: Direct migration requires program conversion. Rockwell’s PLC-5 to Logix Migration Toolkit assists with ladder logic translation, but I/O addressing and some instructions require manual review. Contact us for migration hardware bundles.
Q: What is the maximum I/O for the 1785-L40C15?
A: The PLC-5/40 supports up to 3,072 discrete I/O points across local and remote 1771 chassis.
Q: Do you provide a certificate of conformance?
A: Yes. Certificates of conformance and test reports are available upon request for all units shipped from Konmask.com.
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Contact: support@konmask.com | +0086 19859288691
