The 1756-L55 ControlLogix Processor Module from Rockwell Automation is a widely deployed mid-generation controller designed for industrial automation systems requiring stable logic execution, deterministic performance, and flexible network integration.
Positioned between legacy 1756-L1 series and newer ControlLogix 5580 controllers, the L55 is especially valued in long-life industrial installations where system continuity, proven reliability, and controlled upgrade paths matter more than cutting-edge features. It remains a trusted choice in retrofit and maintenance-driven automation strategies.
Technical Specifications (Including Size & Weight)
| Parameter | Specification |
|---|---|
| Model | 1756-L55 |
| Series | ControlLogix 5555 |
| User Memory | ~2.0 MB (varies by revision) |
| Backplane Current (5.1V DC) | 1.23–1.25 A |
| Backplane Current (24V DC) | 0.014 A |
| Power Dissipation | 5.6–5.7 W |
| Isolation Voltage | 30 V continuous |
| Battery | 1756-BA1 lithium battery |
| Programming Software | RSLogix 5000 (early versions) |
| Network Support | Via communication modules (ENBT, CNB, etc.) |
| Operating Temperature | 0°C to 60°C |
| Storage Temperature | -40°C to 85°C |
| Humidity | 5%–95% non-condensing |
| Dimensions (H × W × D) | 13.3 × 5.1 × 14.5 cm |
| Weight | ~0.34–0.35 kg |
The L55’s compact ControlLogix form factor makes it easy to deploy in existing chassis systems without mechanical redesign.
Recommended Related Models
For upgrades, replacements, or system expansion, the following modules are commonly used alongside the 1756-L55:
- 1756-L61 / L62 ControlLogix CPU (performance upgrade path)
- 1756-ENBT EtherNet/IP Communication Module
- 1756-CNB ControlNet Bridge Module
- 1756-IB16 Digital Input Module
- 1756-OB16 Digital Output Module
Popular Allen-Bradley ControlLogix Models
Within the same generation and ecosystem, engineers often work with:
- 1756-L1 / L1M series legacy processors
- 1756-L55 family CPU modules
- 1756-L71 / L72 modern controllers
- 1756-EN2T high-speed Ethernet modules
- 1756-DNB DeviceNet communication modules
These modules represent a scalable evolution path from legacy control systems to modern industrial automation platforms.
