Description
The 1756-L72 is a ControlLogix 5570 programmable automation controller (PAC) manufactured by Rockwell Automation under the Allen-Bradley brand. It is designed for mid-to-high complexity discrete, motion, process, and safety applications within a ControlLogix chassis.
Equipped with 4 MB of user memory, this processor utilizes a dual-core architecture to optimize user logic execution and background communication handling independently. It operates without an internal battery, instead relying on an onboard energy storage module (ESM) to transfer the running application from volatile memory to internal non-volatile flash storage during a clean power-down cycle.
Technical Specifications
| Parameter | Specification / Value |
| Brand | Allen-Bradley / Rockwell Automation |
| Model Series | ControlLogix 5570 |
| Part Number | 1756-L72 |
| User Memory | 4 MB (for data and logic) |
| I/O Memory | 0.98 MB |
| Optional Non-Volatile Memory | 1 GB (1784-SD1 included) or 2 GB (1784-SD2) Secure Digital card |
| Onboard Communications | 1 x USB 2.0 Port (Full speed, peripheral configuration only) |
| Maximum Digital I/O Capacity | 128,000 points total |
| Maximum Analog I/O Capacity | 4,000 points total |
| Controller Tasks | 32 Tasks (100 Programs per task, event tasks supported) |
| Backplane Current Draw | 800 mA at 1.2 V DC
5 mA at 5.1 V DC |
| Power Dissipation | 2.5 W |
| Weight | 0.25 kg (0.55 lb) |
Field Application and System Integration Notes
Network Module Dependency
Unlike newer ControlLogix 5580 controllers (e.g., 1756-L82E), the 1756-L72 does not feature an onboard Ethernet port.
- Communication Interface: The integrated USB port is designated strictly for temporary programming, firmware flashing, and diagnostics.
- Backplane Bridging: To connect the 1756-L72 to an EtherNet/IP, ControlNet, or DeviceNet network, you must install a separate, dedicated communications bridge module (such as a 1756-EN2TR, 1756-EN3TR, or 1756-CN2R) within the same local ControlLogix chassis.
Energy Storage Module (ESM) Considerations
The 1756-L72 ships with a standard 1756-ESMCAP capacitor module installed, completely eliminating the maintenance overhead of lithium battery schedules.
- Power-Down Cycle: When primary 1756 rack power drops, the ESM delivers a temporary charge that allows the controller to write its active RAM runtime state directly into the internal flash memory.
- De-energizing Restrictions: For mining or hazardous application constraints where residual energy storage is restricted, the standard module can be replaced with the 1756-ESMNK (No-Capacitor/No-Energy) module. Note that using an “NK” variant means the controller will lose its program if powered down without an active, pre-configured SD card automatic-load routine.
Firmware and Software Version Limits
- Software IDE: Programming the 1756-L72 requires RSLogix 5000 (Version 20) or Studio 5000 Logix Designer (Version 21 and higher).
- Firmware Coordination: Always coordinate the firmware kit revision loaded onto the processor with your specific Studio 5000 project revision. Firmware flashing should be conducted over a stable EtherNet/IP network connection or directly via the front USB port using ControlFlash or ControlFlash Plus utilities.
Commercial and Procurement Data
- Product Condition: New Original (Factory Sealed) or Refurbished/Tested Surplus.
- Standard Warranty: 12-month comprehensive warranty from the date of supply.
- Estimated Lead Time: In-stock hardware typically packs and ships within 1 to 2 business days.
- Pricing Notice: Prices fluctuate based on market availability, regional safety standards, and global supply lines. Contact our industrial automation division for a formal, time-stamped commercial quotation.
