CPU specifications and I/O architecture
The Siemens 6ES7288-1ST30-0AA0 is a current-production S7-1200 CPU with 18 KB of program memory and a 144-byte I/O image that maps 256 bits of digital inputs and 56 words of analog inputs, with matching capacity for outputs. The memory type is DDR, and the CPU supports programming in LAD, FBD, and STL, with RAM and Flash memory onboard. The I/O image is per-device limited to 128 bytes input and 128 bytes output, so the total 144-byte image covers the CPU's local I/O plus a portion of any expansion. Forcing is supported for commissioning and troubleshooting.
Environmental range and real-time clock
The real-time clock is maintenance-free with a 7-day backup time, and the RTC requires 7 days of powered operation to reach full charge. The clock has no battery backup, so the capacitor holds the time during power loss within that window. Transformer isolation rated at 1,500 V AC separates the CPU logic from the I/O and communication circuits.
Communication interfaces and motion control
PROFINET IO is built in with autocrossing and autonegotiation, supporting up to 128 bytes of input and output data per device. The minimum PROFINET update time is 4 ms, though actual performance depends on the IO device count and configured data volume. An RS485 port runs at up to 187.5 kbps for connection to Modbus RTU networks or drives. PROFIBUS DP is available via an optional CM DP module. For motion and high-speed counting, the CPU supports up to 6 single-phase HSCs at 200 kHz and 1 at 30 kHz, or 4 A/B phase encoders at 100 kHz and 1 at 20 kHz. These are parameterizable and can be used for position capture or frequency measurement.
Control functionality and compliance
A built-in PID controller handles up to 8 loops with continuous or binary outputs and automatic/manual mode. The CPU can act as both a PROFINET IO client and server. CE marking is listed, indicating compliance with applicable EU directives for industrial environments.