CPU 226 COMPACT UNIT 6ES7216-2BD23-0XB0 6ES7 216-2BD23-0XB0 6ES7216-2BD23-OXBO

Siemens 6ES7216-2BD23-0XB0 | SIMATIC S7-200 CPU 226 — AC Supply / 24 DC Inputs / 16 Relay Outputs / 16KB Programme / 2 × RS-485 / Discontinued Spare

CPU 226 — The Largest S7-200 in One Housing

The CPU 226 is the highest-capacity compact controller in the S7-200 range. Twenty-four digital inputs and 16 relay outputs integrated directly into the CPU housing — the most onboard I/O of any S7-200 CPU. For machine control applications that fit within this I/O count, the CPU 226 provides a complete solution without any expansion module.

The AC power version draws its operating power from 100–230V AC mains directly. This eliminates the need for a separate 24V DC switched-mode power supply for the CPU in panels where AC mains is the primary power distribution. The wider panels using both AC and DC supply still benefit — fewer components, simpler design.

Sixteen relay outputs cover the widest load variety: motor starter coils at 230V AC, solenoid valves at 24V DC, indicator lamps at mixed voltages — all connected to the relay contacts without voltage-matching concerns or interposing hardware. The relay contacts are galvanically isolated from the CPU's logic supply, protecting the PLC from field-level voltage transients on the load side.

Two RS-485 ports are the communication backbone. Port 1 is the PPI programming connection for STEP 7 Micro/WIN. Port 2 is user-programmable — operating in PPI for HMI panels, Modbus RTU for drives and instruments, or Freeport for custom ASCII protocol devices. With 7 expansion module slots available (the maximum in the S7-200 family), the CPU 226 scales to handle larger installations when the onboard I/O is not enough.

Key Specifications

Application Scenarios

Packaging and conveyor systems: High local I/O count manages sensor inputs, motor contactors, reject gates, and indicators. The second RS-485 port connects an operator text

display or HMI panel without consuming a programming port.

Pump stations and utility control: Pressure, level, and flow contacts connect to 24 inputs; pump motor contactors and valve solenoids connect to relay outputs. AC supply simplifies the panel design for installations without 24V DC distribution.

Modbus-connected processes: The user-programmable RS-485 port runs Modbus RTU master to a variable speed drive, energy meter, or remote analogue transmitter — handled through STEP 7 Micro/WIN's Modbus library without custom code.

Legacy S7-200 machine maintenance: CPU 226 was deployed extensively through the 2000s. An identical replacement preserves the onboard I/O address map and serial port configuration, minimising recommissioning time and programme modification.

FAQ

Q1: What is the -0XB0 suffix and how does it differ from -0XA0?

The -0XB0 is a China-produced S7-200 variant with CE certification. The -0XA0 is the European-produced variant with CE plus UL/cUL certifications. Both are electrically and functionally identical — same I/O, same memory, same RS-485 interface. They are direct substitutes for most applications; confirm the certification requirement for the installation site.

Q2: What expansion modules are compatible, and how many can be added?

Up to 7 expansion modules connect via the right-side expansion bus. Available types: digital input and output modules (relay and transistor), analogue I/O modules, RTD and thermocouple modules, and specialty modules. The CPU 226 supports the full 7-module maximum — the largest expansion capacity in the S7-200 family.

Q3: What programming environment is required?

STEP 7 Micro/WIN — the dedicated S7-200 software. Neither STEP 7 Classic (for S7-300/400) nor TIA Portal (for S7-1200/1500) programme the S7-200. STEP 7 Micro/WIN supports ladder logic, FBD, and statement list, plus the CPU's built-in libraries for PID, Modbus, high-speed counting, and PTO/PWM.

Q4: What protocols does the second RS-485 port support?

In Freeport mode: full programme-controlled serial port, any ASCII or RTU-based protocol. STEP 7 Micro/WIN provides library blocks for Modbus RTU master and slave, and USS protocol for Siemens drives. PPI mode for Siemens HMI panels. The port does not support PROFIBUS DP without an add-on CP module.

Q5: Where is the 6ES7216-2BD23-0XB0 sourced?

Through the S7-200 aftermarket — legacy automation suppliers, industrial surplus dealers, and specialist S7-200 parts distributors globally. The CPU 226 is one of the most commonly available S7-200 spares. Confirm the -0XB0 variant and load the programme from a STEP 7 Micro/WIN backup into the replacement unit rather than relying on programme retention.