Siemens 6ES5256-3AB11 PLC | 16 Inputs 16 Outputs

Physical Dimensions and Mounting Specifications

The Siemens 6ES5256-3AB11 serves as a compact PLC for small automation tasks. This controller measures 250mm in height, 25mm in width, and 150mm in depth. You can mount this unit on a standard 35mm DIN rail inside any control cabinet. The PLC weighs 0.46 kilograms , allowing for easy one-person installation.

Internal Architecture and Component Density

The Siemens 6ES5256-3AB11 contains 168 individual components on its four-layer PCB. An 8-bit microprocessor runs user programs at 5 MHz clock speed. Six static RAM chips provide 16 KB of work memory for program execution. Additionally, two EPROM chips store 8 KB of firmware for system operations.

Energy Storage and Program Retention

This PLC stores 8.6 joules across five electrolytic capacitors. This energy reserve maintains program execution for up to 25 milliseconds during power dips. The storage also preserves retentive variables while the system recovers from faults. Consequently, critical process values survive brief supply interruptions without external battery backup.

Parameter	Value	Unit
Dimensions (H x W x D)	250 x 25 x 150	mm
Weight	0.46	kg
PCB layer count	4	layers
Total components	168	pieces
Microprocessor speed	5	MHz
Microprocessor bit width	8	bits
Static RAM (work memory)	16	KB
EPROM (firmware)	8	KB
Electrolytic capacitors	5	units
Total energy storage	8.6	J
Program hold-up time	25	ms
Digital inputs	16	channels
Digital outputs	16	channels
Input voltage range	20–30	V DC
Output current per point	0.5	A
Scan time (1K statements)	25	ms
Timer/counter capacity	64 each	–
Backplane current draw	280	mA
LED indicators	8	units

Interface and Connectivity Features

The Siemens 6ES5256-3AB11 provides one 20-pin screw terminal block for I/O wiring. A single 20-pin IDC header links the PLC to the S5 backplane. You will also find one 9-pin D-sub connector for programming device connection. Each terminal accepts AWG 24 to AWG 16 copper wire for secure connections.

Processing Capabilities and Execution

This controller executes ladder logic and statement list programs efficiently. The PLC processes up to 256 I/O points using its 16 onboard inputs and outputs. You can configure 64 timers and 64 counters for standard control applications. Furthermore, the module supports bit logic operations for fast discrete control tasks.

Onboard I/O and Features

The Siemens 6ES5256-3AB11 includes 16 digital inputs and 16 digital outputs on the module. Inputs include 3ms debounce filtering for noise immunity in harsh environments. Outputs handle 0.5A continuous with short-circuit protection built into each channel. This onboard I/O provides complete control for small machines without additional modules.

Diagnostic and Status Indication

Eight LED indicators provide comprehensive feedback for PLC and I/O status. Green RUN confirms normal program execution and processor activity. Amber STOP indicates the controller is in stop mode with no program running. Red FAULT lights up for any program error or hardware failure. Additional LEDs show I/O status for select input and output channels.

Programming and System Integration

You program the Siemens 6ES5256-3AB11 using STEP 5 software on a programming device. The PLC connects to the programmer through the 9-pin RS-232 port on the front panel. You can perform online monitoring, program upload, and download through this interface. The controller supports standalone operation without a separate CPU rack.

Environmental Specifications and Compliance

You can operate this PLC from 0°C to 60°C ambient temperature without derating. Storage temperature ranges from -20°C to 70°C for long-term preservation. Non-condensing humidity tolerance spans 10% to 95% for industrial environments. This controller meets DIN 19240 and IEC 61131-2 standards for programmable logic controllers.