The Allen-Bradley 1756-L75 Programmable Automation Controller (PAC) is part of the ControlLogix controller platform that is designed for use in large and complex applications. The 1756-L75 is specifically a Logix processor that accepts downloading of user program developed in Ladder Diagram (LD), Structure Text (ST), Function Block Diagram (FBD) and Sequential Function Chart (SFC).

The 1756-L75 is the most powerful processor from the Logix 5570 controller series as this controller comes with a 32MB user memory and 0.98 Input and Output memory. With this capability, user programs that are custom designed to implement sophisticated applications may be implemented using this controller. Additionally, the 1756-L75 is one of the controllers compatible for use with the PlantPAx Distributed Control System (DCS) by Rockwell Automation. The 1756-L75 is also shipped with One (1) 1784-SD1 Secure Digital (SD) card with non-volatile memory area amounting to 1 GB.

The 1756-L75 complies with the previously accepted eco-friendly solution of using energy storage modules for retaining contents of the volatile memory, instead of using traditional batteries. Additionally, this controller is capable of being downloaded up to 32 Controllers tasks wherein each task may contain up to 100 programs with all event triggers supported.

The 1756-L75 can be used to interface up to 128,000 Digital I/O and 4000 Analog I/O. The embedded USB ports may be used to download initial configuration to the controller and capable of transmission rate up to 12 Mbps. This controller may be used in simples or redundant controller configuration and installed to any slot of the 1756 ControlLogix chassis.

The 1756-L75 controller can handle up to a maximum of 500 controller connections. It also has several communication options available, such as Third-party process and device networks, EtherNet/IP, SynchLink, ControlNet, Remote I/O, DeviceNet, and Data Highway Plus.

It also ships with three capacitor energy storage modules, two of which are removable and one is non-removable. The removable 1756-ESMCAP module ships already installed with the controller. The other removable module is the 1756-ESMNSE that has no residual WallClockTime power backup. The 1756-ESMNRM is the non-removable module that secures the controller by preventing SD card use and USB connection.

It has a maximum digital I/O and total I/O of 128,000 each and a maximum analog I/O of 4,000. The current draw of this controller is 5 mA at 1.2V DC and 800 mA at 5.1V DC. It has a power dissipation of 2.5 W and a continuous isolation voltage of 30V. It has a thermal dissipation of 8.5 BTU/hr and a relative humidity of 5% to 95% (noncondensing). The controller has a maximum surrounding air temperature of 60 Degrees Celsius, an operating temperature range of 0 to 60 Degrees Celsius, and a non-operating temperature range of -40 to 85 Degrees Celsius. Its vibration is 2 g at 10 to 500 Hz, non-operating shock is 50 g that goes down to 45 g when an SD card is installed, and an operating shock of 30 g.