The Allen-Bradley 1756-L72S is a GuardLogix 5570 controller that is a part of the Logix5000 family of controllers. It is a ControlLogix controller with safety control functions. It is a dual processor solution that must be used with a 1756-L7SP safety module to meet SIL 3 or Cat. 4/PLe safety standards. The safety partner controller is automatically configured, benefitting a single project. It has great processing capabilities and speed for motion and high-performance logic. It has a USB port for communication. It can support up to 500 controller connections. The 1756-L72S controller has 4MB of user memory, 2MB of Safety Memory, and 0.98MB of I/O memory. It can support 128,000 digital I/O and 4000 Analog I/O. It draws a current of 5mA at 1.2V DC and 800mA at 5.1V DC. It has a power dissipation of 2.5W and thermal dissipation of 8.5 BTU/hr. It weighs 0.55lbs and has an isolation voltage of 30V (continuous) for basic insulation. It can be installed in any slot of a ControlLogix 1756 Chassis and multiple controllers can also be installed in the same chassis. For safe communication, it uses ControlNet, DeviceNet, or EtherNet/IP networks. The 1756-L72S controller can control or monitor I/O over the backplane or through I/O links. For controller diagnostics, it has a front display that provides runtime information. It functions using energy storage modules, meaning that lithium batteries are not needed. A 1 GB (1784-SD1) Secure Digital card comes pre-installed as an optional non-volatile storage which can be expanded up to 2 GB (1784-SD2).

The Allen-Bradley 1756-L72S is a 5570 GuardLogix Programmable Automation Controller (PAC). This controller features standard and safety controller capabilities. This controller is the primary controller, used with a safety partner with catalog number 1756-L7SP or 1756-L7SPK to achieve Safety Integrated Level (SIL) Category Level (CL) 3/Performance Level e (PLe) /Cat. 4. Rating. Using the 1756-L72S, standard and safety projects are integrated in a single file unlike dedicated safety controllers.

The 1756-L72S features high-capacity standard memory and a dedicated safety memory. These memory areas amount to 4 Megabytes user memory, 2 Megabytes Safety memory, I/O memory of 0.98 Megabytes and 1 Gigabyte non-volatile memory which is provided by the 1784-SD1 that ships with the controller. It enables the 1756-L72S to interface up to a maximum of 128,000 Input and Output (I/O) signals which may be composed of 128,000 Discrete I/O along and 4000 Analog I/O.

The 1756-L72S is an environment-friendly controller, as it is equipped with modern energy storage modules rather than traditional Lithium batteries to retain the Random Access Memory (RAM). These memory storage modules include 1756-ESMCAP which ships with the controller; 1756-ESMNSE which is a removable, no residual WallClockTime power backup or 1756-ESMNRM that is nonremovable and helps prevent USB connection and SD card use to help secure the controller.

The 1756-L72S may be installed to any standard or conformally-coated ControlLogix chassis such as 1756-A4, 1756-A4K, 1756-A7, 1756-A7K, 1756-A10, 1756-A10K, 1756-A13, 1756-A13K,1756-A17, and 1756-A17K, as well as standard power supplies such as 1756-PA50, 1756-PA72, 1756-PA72K, 1756-PA75, 1756-PA75K, 1756-PB50, 1756-PB72, 1756-PB72K, 1756-PB75, and 1756-PB75K.