Siemens 6ES5944-7UA21 SIMATIC S5 IO Module System

Siemens 6ES5944-7UA21 is a CPU 944 central processing unit for the SIMATIC S5-115U family, delivering a 96 KB RAM footprint to run ladder logic and basic data handling within legacy S5 systems. This module is part of the SIMATIC S5 IO Module System and slots into the S5 backplane to drive the S5-115U controller’s program execution and I/O management. It provides two serial interfaces (2 x TTY) for connecting programming devices or operator terminals, enabling maintenance and diagnostics without removing the CPU itself. As a CPU944 configuration within the 6ES5944 family, the 6ES5944-7UA21 is designed for replacement in aging S5 installations, supporting continued operation of legacy lines that rely on Siemens S5 technology. This model is typically encountered in older automation setups where S5-115U processors are still in service, making it a relevant option for repairs, spares, or restorations of vintage Siemens equipment.