Siemens 6ES72881ST400AA1 PLC Manufacturer Series S7 ET 200 CPU Output Type Digital Communication Port PROFINET,ETHERNET Brand SIEMENS I/O Points 24 DI/16 DO Usage/Application Automation The Siemens S7-200 SMART CPU ST40 (Part Number: 6ES72881ST400AA1) is a compact and versatile Programmable Logic Controller (PLC) from the Siemens S7-200 SMART series. This CPU is designed to provide an efficient, cost-effective solution for small and medium-sized automation applications. The S7-200 SMART series is intended for users who need reliable performance in tight spaces or for tasks that don't require high-end processing power.