The 1756-L73S is an Allen-Bradley GuardLogix 5570 Programmable Automation Controller (PAC). This controller features capability of executing standard and safety functions. Standard functions are caried out by the controller itself while safety functions are separately communicated to the partner controller with catalog number 1756-L7SP. This primary controller is required to enable the safety functionalities of the GuardLogix controller and must be installed to the immediate available slot, beside the 1756-L73S.

The 1756-L73S comes with 8 MB standard user memory, Safety memory amounting to 4MB, and I/O memory of 0.98 MB. It ships with 1756-SD1 Secure Digital (SD) card with memory size amounting to 1 GB non-volatile memory. The embedded communication port of the 1756-L71S is a single USB communication port that may be used only for programming, hardware configuration and online editing, it cannot be used for industrial communication. With the embedded memory capability, the 1756-L73S supports maximum of 128,000 Discrete I/O points and 4000 Analog I/O points.

The 1756-L73S is an environmentally friendly processor as it is installed with 1756-ESMCAP capacitor energy storage module which is removable and pre-installed within every controller. It may be replaced with 1756-ESMNSE or 1756-ESMNRM. All this energy storage module are capacitor based, eliminating the need of Lithium batteries.

The 1756-L73S when used with the appropriate partner controller, is certified SIL 3 and PLe, compatible for similarly safety rated applications. Standard controller functions may be programmed using Relay Ladder Logic (RLL), Structured Text, Function Block Diagram, Sequential Function Chart (SFC) while for ssafety task, only Relay Ladder Logix is permitted.

The safety partner controller is automatically configured providing major benefits to a single project. It has greater 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-L73S controller has 8MB of user memory, 4MB 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 of 800mA at 5.1V DC. Its power dissipation is 2.5W and its thermal dissipation is 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-L73S controller can control or monitor I/O over the backplane or through the I/O links. For controller diagnostics, it has a front display that provides runtime information. It uses energy storage modules, which means 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).