Product Overview

The Siemens 6ES5255-3AC11, also known as the MONA-C (Monitoring and Control) or IP255 display module, is a specialized operator interface and display unit designed for the Siemens SIMATIC S5 series of programmable logic controllers. This module functions as a local HMI (Human-Machine Interface) that provides real-time process monitoring, parameter adjustment, and diagnostic capabilities directly at the machine or control rack, eliminating the need for external programming devices or central SCADA workstations for routine operations . The Siemens 6ES5255-3AC11 is engineered for seamless integration into the S5 backplane bus architecture, enabling it to communicate directly with the CPU through the rack’s backplane without additional cabling or external power supplies .

The Siemens 6ES5255-3AC11 features a clear alphanumeric LCD display—commonly supporting 2 lines of 16 characters or up to 4 lines of 80 characters depending on configuration—alongside a membrane keypad with tactile feedback keys for scrolling through parameters, editing setpoints, and acknowledging alarms . This display module occupies a single slot in S5-100U, S5-95U, S5-135U, and S5-155U rack systems, making it a versatile solution for local monitoring across the SIMATIC S5 family . As the SIMATIC S5 series has been officially discontinued for many years, the Siemens 6ES5255-3AC11 is now exclusively available through legacy spare parts channels, representing a critical resource for facilities continuing to operate S5-based equipment where full system migration is not yet economically or logistically feasible .

Technical Specifications