CompactLogix (1769) Processor Selection Guide
Allen-Bradley CompactLogix 5370 controllers under Bulletin 1769 offer scalable, compact, and cost-effective control for small to mid-sized applications. Designed as part of Rockwell Automation's Integrated Architecture system, they offer seamless compatibility with Studio 5000, support for Ethernet/IP, DeviceNet, serial protocols, and flexible I/O expansion.
Processor Series Breakdown
A) CompactLogix 5370 L1
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Embedded 24V DC power supply (Series A: non-isolated; Series B: isolated)
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Dual Ethernet/IP ports (Linear or DLR)
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USB port for firmware and programming
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Optional SD card (1GB included, 2GB available)
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Memory up to 1MB
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Uses 1734 POINT I/O for expansion
| Model | User Memory |
|---|---|
| 1769-L16ER-BB1B | 384 KB |
| 1769-L18ER-BB1B | 512 KB |
| 1769-L18ERM-BB1B / -BB1BK | 512 KB |
| 1769-L19ER-BB1B / -BB1BK | 1 MB |
B) CompactLogix 5370 L2
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40% reduced panel space
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Integral 24V DC power supply
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Two Ethernet ports + USB
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SD card support (1GB included)
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Embedded I/O (digital, analog, HSC)
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Supports 1769 Compact I/O modules
| Model | User Memory |
| 1769-L24ER-QB1B | 0.75 MB |
| 1769-L24ER-QBFC1B / -QBFC1BK | 0.75 MB |
| 1769-L27ERM-QBFC1B | 1.0 MB |
C) CompactLogix 5370 L3
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External 24V DC 1769 power supply
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Up to 5MB user memory
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SD card support (1GB standard, 2GB optional)
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No embedded I/O; supports 1769 Compact I/O
| Model | User Memory |
| 1769-L30ER / -ERK | 1 MB |
| 1769-L30ERM / -ERMK | 1 MB |
| 1769-L33ER / -ERK | 2 MB |
| 1769-L33ERM / -ERMK | 2 MB |
| 1769-L36ERM | 3 MB |
| 1769-L37ERM / -ERMK | 4 MB |
| 1769-L38ERM / -ERMK | 5 MB |
Compact GuardLogix 5370 (L3S)
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Up to SIL 3/PL(e)
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Built-in safety memory
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Includes standard and safety control in one unit
| Model | User / Safety Memory |
| 1769-L30ERMS | 1 MB / 0.5 MB |
| 1769-L33ERMS / -ERMSK | 2 MB / 1 MB |
| 1769-L36ERMS | 3 MB / 1.5 MB |
| 1769-L37ERMS / -ERMSK | 4 MB / 1.5 MB |
| 1769-L38ERMS / -ERMSK | 5 MB / 1.5 MB |
Armor CompactLogix & Armor Compact GuardLogix
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IP67-rated for harsh environments
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On-machine mounting
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Motion and safety control included (GuardLogix)
| Model | User / Safety Memory |
| 1769-L33ERMO | 2 MB |
| 1769-L36ERMO | 3 MB |
| 1769-L37ERMO | 4 MB |
| 1769-L38ERMO | 5 MB |
| 1769-L33ERMOS | 2 MB / 1 MB |
| 1769-L36ERMOS | 3 MB / 1.5 MB |
| 1769-L37ERMOS | 4 MB / 1.5 MB |
| 1769-L38ERMOS | 5 MB / 1.5 MB |
Selection Considerations
1. Application Requirements
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L1: Small to mid-size machine control with POINT I/O
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L2: Mid-performance controls with built-in I/O
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L3: High-performance systems with full modular I/O
2. Communication Needs
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All support Ethernet/IP (DLR, Linear)
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L2 & L3 support DeviceNet
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Serial options available by model
3. I/O Compatibility
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L1: Embedded digital I/O + 1734 POINT I/O
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L2: Embedded analog/digital/HSC + 1769 Compact I/O
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L3: Only 1769 Compact I/O
4. Motion Control
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L1: 1769-L18ERM-BB1B/K – 2 axes CIP motion
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L2: 1769-L27ERM-QBFC1B – 4 axes CIP motion
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L3:
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L30ERM – 4 axes
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L33ERM – 8 axes
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L36ERM and up – 16 axes
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5. Hazardous Environments
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NSE models (e.g., 1769-L30ER-NSE) for mining/oil
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Less than 200µJ residual energy
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No real-time clock during power cycles
Conclusion The 1769 CompactLogix 5370 family offers extensive flexibility, from embedded I/O to SIL 3 safety, scalable motion, and IP67-rated models for harsh conditions. Whether you're designing a compact machine, a high-speed production skid, or a hazardous mining solution, there's a CompactLogix 5370 model that fits.
Need Help Selecting a 1769 CompactLogix Processor? Contact us today:
PLG Automation
Email: sales@plgautomation.com
Phone: 800-906-9271