Product Overview
The Allen-Bradley 1756-L72S is a GuardLogix 5570 Programmable Automation Controller (PAC) from the Logix5000 family. This processor integrates standard and safety control in a single project, eliminating the need for separate safety controllers. With 4MB of user memory and 2MB of dedicated safety memory, the 1756-L72S meets the demands of high-performance motion and safety applications.
Designed for SIL 3, PLe, and Category 4 safety ratings, this controller works with a 1756-L7SP safety partner to deliver robust safety functions. The 1756-L72S also features an integrated energy storage module (ESM) that replaces traditional lithium batteries, making it an environmentally friendly choice for modern automation systems.
Technical Specifications
Below are the key specifications for the Allen-Bradley 1756-L72S, sourced directly from the manufacturer's data:
| Specification |
Value |
| User Memory |
4 MB |
| Safety Memory |
2 MB |
| I/O Memory |
0.98 MB |
| Non-Volatile Memory |
1 GB (ships with controller) |
| Maximum I/O |
128,000 |
| Maximum Analog I/O |
4,000 |
| Maximum Digital I/O |
128,000 |
| Number of Standard Tasks |
31 |
| Number of Safety Tasks |
1 |
| Programs per Task |
100 |
| Event Tasks |
All triggers |
| Built-in Communication |
1 USB port |
| Current Draw (1.2V DC) |
5 mA |
| Current Draw (5.1V DC) |
800 mA |
| Power Dissipation |
2.5 W |
| Thermal Dissipation |
8.5 BTU/hr |
| Isolation Voltage |
30V continuous |
| Enclosure |
None (Open-Style) |
The 1756-L72S supports up to 500 controller connections, making it ideal for large, distributed systems.
Applications
The Allen-Bradley 1756-L72S excels in applications requiring both standard and safety control. Typical use cases include:
-
Machine Safety: Integrate safety interlocks and emergency stops with standard machine logic in a single controller, reducing wiring and complexity.
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Process Automation: Manage batch processes that demand high availability and SIL 3-rated safety functions, such as chemical or pharmaceutical production.
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Motion Control: Execute coordinated multi-axis motion with the processing power needed for high-speed, high-precision applications.
Because the 1756-L72S combines standard and safety tasks, it simplifies project development and reduces the total cost of ownership.
Installation & Setup
Install the 1756-L72S into any slot of a ControlLogix 1756 chassis (standard or conformally-coated). Multiple controllers can reside in the same chassis. Connect the safety partner 1756-L7SP to enable safety functions; the system automatically configures the partner for a single project. Use the built-in USB port for local programming and diagnostics. Secure the processor with the included 1784-SD1 SD card for non-volatile memory; this card can be expanded to 2 GB with the 1784-SD2.
Maintenance & Reliability
The 1756-L72S uses energy storage modules (ESM) instead of batteries, eliminating periodic battery replacement and reducing maintenance downtime. The integrated 1756-ESMCAP provides backup during power loss, while optional modules (1756-ESMNSE, 1756-ESMNRM) offer alternative configurations. The open-style enclosure requires proper panel protection; ensure the chassis is mounted in a clean, dry environment to maintain reliability.
Compatibility & Integration
As part of the ControlLogix family, the 1756-L72S integrates with a wide range of I/O modules, communication interfaces, and third-party devices. It communicates over ControlNet, DeviceNet, or EtherNet/IP networks for safe and standard data exchange. The controller supports up to 128,000 digital I/O and 4,000 analog I/O, providing scalability for large applications.
Buying Guide
When purchasing the Allen-Bradley 1756-L72S, verify that you have the required safety partner (1756-L7SP) and compatible chassis. Consider your memory and I/O needs to ensure the 1756-L72S meets your application requirements. For a reliable source, PLC Source PRO offers genuine Allen-Bradley products with competitive pricing and fast delivery.