The 1756-M3 modules is an expansion memory module that is designed and produced by Allen-Bradley/Rockwell Automation. As it can be seen from the product code itself, the module is part of the Bulletin 1756 product line and it is intended for the ControlLogix systems. The ControlLogix environment includes processors, amplifiers, controllers, digital/analog I/O modules, and communication modules along with memory modules. The 1756 ControlLogix product family offers electronic keying, enhanced safety functions, point-level output fault states, optimized communication, real-time channel sampling, and isolated and non-isolated module types. The 1756-M3 memory module is used with controllers that have a memory capacity from 750 kilobytes to 32 megabytes. The backplane current of these controllers is 1.20 to 1.25 Amps at 5.1 Volts DC and it is 0.014 Amps to 14 milliAmps at 24 Volts DC.

The 1756-M3 memory module is made for operating conditions that include an operating temperature range of 0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit) and a storage temperature range of -40 to 85 degrees Celsius (-40 to 185 degrees Fahrenheit). The relative humidity levels should be between 5 and 95% in non-condensing conditions. The IEC temperature code for the unit is T4A/T4 and the unit belongs to the Class A/Group 1 emission group. The 1756-M3 memory module tolerates a vibration of 2 G at 10 to 500 Hertz and 30 G of shock. The unit weighs around 0.22 kilograms (7.7 ounces) and it mounts in a chassis like other components from this category. The module includes an ESD immunity of 6 kiloVolts for indirect contact discharge and of 8 kiloVolts for air discharge per the IEC 61000-4-2 standards.