Siemens 6ES7223-1BH32-0XB0 — SM 1223 Digital I/O Buying Guide

By Abdullah Zahid
12 min read
Siemens 6ES7223-1BH32-0XB0 SM 1223 digital I/O expansion module for S7-1200 PLC in cabinet installation

Siemens 6ES7223-1BH32-0XB0 — SIMATIC S7-1200 Digital I/O SM 1223, 8 DI / 8 DO, 8 DI 24 V DC Sink/Source, 8 DO Transistor 0.5 A: Specifications, Installation, and Selection Guide

If you are already running an S7-1200 platform and need to add digital I/O capacity without swapping your CPU or adding a remote I/O station, the Siemens 6ES7223-1BH32-0XB0 is the direct-mount expansion module most controls engineers reach for first. It adds 8 inputs and 8 transistor outputs rated at 0.5A per channel, all at 24V DC, in a 45mm-wide housing that snaps onto the right side of your existing CPU backplane. The decision that typically brings engineers to this page is a simple one: does the SM 1223 have enough output current for their connected loads, or do they need to step up to a relay-output variant?

If you have already confirmed this is the right part, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the 6ES7223-1BH32-0XB0 — and Who Shouldn't

The Siemens 6ES7223-1BH32-0XB0 is the right choice for engineers expanding an existing S7-1200 system with additional digital switching capacity. It is a strong fit when all of the following apply:

  • Your controller is an S7-1200 CPU — this module is not compatible with S7-300, S7-1500, or other families
  • Your field devices operate at 24V DC and your power supply delivers a stable 20.4 to 28.8V DC
  • Your output loads draw no more than 0.5A per channel and no more than 4A total per output group
  • All input signals are digital on/off — proximity switches, limit switches, push buttons, or relay contacts
  • Your cable runs stay within 500m shielded or 150m unshielded for outputs, and 500m shielded or 300m unshielded for inputs
  • You have external fusing or overload protection available — the SM 1223 has no built-in short-circuit protection

If your loads require isolation or draw more than 0.5A per point, the relay-output SM 1224 is the correct alternative. If any of your signals are analog — temperature, pressure, flow — look at the SM 1231 or SM 1232 instead.

On this page:

What the 6ES7223-1BH32-0XB0 Actually Does in a Running System

The Siemens 6ES7223-1BH32-0XB0 is a digital I/O expansion module — not a standalone controller. It mounts directly to the right side of an S7-1200 CPU via the backplane connector and extends the CPU's I/O capacity by 8 inputs and 8 outputs without requiring additional communication protocols, gateways, or separate power supplies beyond 24V DC. This is the practical reason it appears in so many cabinet builds: it is the lowest-overhead way to add 16 digital points to a system that already exists.

The 8 inputs accept 24V DC signals and are configured as sink/source, meaning they work with both positive-switching and negative-switching field devices without rewiring. Input delay is selectable in STEP 7 TIA Portal from 0.2ms up to 12.8ms, giving engineers control over noise filtering versus response speed. The 8 outputs are transistor-type, each rated at 0.5A, grouped individually for maximum flexibility. One critical point that catches engineers off guard: there is no integrated short-circuit protection. External fusing or overload protection is mandatory on every output group before commissioning.

The module carries an IP20 rating, which means it requires cabinet mounting — it is not rated for washdown, wet, or explosive environments. At 45mm wide, 100mm tall, and 75mm deep, it fits alongside other S7-1200 signal modules in a compact DIN-rail enclosure without consuming excessive panel space.

Typical S7-1200 System Architecture With the SM 1223

The 6ES7223-1BH32-0XB0 sits immediately to the right of the S7-1200 CPU on the backplane, feeding and receiving digital signals between the controller and field devices without any intermediate communication layer.

  • 24V DC power supply feeds both the S7-1200 CPU and the SM 1223 module directly
  • S7-1200 CPU connects to the SM 1223 via the integrated backplane bus connector — no separate communication cable required
  • SM 1223 input terminals connect to field sensors: proximity switches, limit switches, push buttons, relay contacts
  • SM 1223 output terminals connect through external fuses to field actuators: solenoid valves, motor contactors, indicator lights, small relays
  • Additional SM 1223 modules (or other S7-1200 signal modules) can be stacked further to the right of the first module, subject to the CPU's maximum I/O expansion limit

Industries and Applications Where This Module Earns Its Place

Packaging line engineers are among the most frequent users of the 6ES7223-1BH32-0XB0. A common scenario is an OEM adding fill-line solenoid control and cylinder position sensing to an existing S7-1200 without replacing the CPU — the SM 1223 adds the 8 outputs needed to drive additional pneumatic valves and the 8 inputs to monitor the corresponding cylinder switches.

In bottling and food and beverage facilities, the module handles ingredient hopper valve sequencing, conveyor motor start/stop circuits, and zone isolation logic. Its sink/source input capability simplifies integration with different sensor manufacturers whose output transistors may be PNP or NPN.

Machine tool builders and system integrators frequently standardize on S7-1200 plus SM 1223 for mid-range automation to reduce spare-parts inventory complexity. A single module covers workpiece clamping solenoids, tool changer actuator feedback, and spindle enable circuits in a single 45mm-wide package.

Retrofit and renovation projects particularly benefit from the SM 1223. When a plant needs to expand an existing machine's I/O count, adding an SM 1223 avoids a full PLC replacement and the associated retraining costs. Test stand applications also appear regularly — controlling multiple test-point solenoids and collecting pass/fail digital signals from a compact, proven module.

Application Typical Deployment
Packaging line upgrade SM 1223 added to existing S7-1200 to control solenoids and monitor cylinder switches without CPU replacement
Bottling facility retrofit 8 proximity sensor inputs and 8 conveyor motor start/stop outputs added to existing controller
Machine tool builder standardization S7-1200 plus SM 1223 as standard I/O platform across a product family to simplify spare parts
Plant renovation project SM 1223 added to legacy machine's S7-1200 to expand capacity and avoid full PLC replacement
Test stand expansion Multiple test-point solenoids controlled and pass/fail digital signals collected via SM 1223

Electrical and Physical Specifications: What Engineers Need to Know Before Ordering

Parameter Value
Supply Voltage (Rated) 24V DC
Supply Voltage Range 20.4 to 28.8V DC
Power Consumption 2.5W
Digital Inputs 8, 24V DC, sink/source, IEC 61131 type 1
Digital Outputs 8, transistor, 0.5A per channel
Input Delay (Selectable) 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, or 12.8 ms
Output Delay 50µs to 200µs
Total Output Current Per Group 4A
Max Cable Length — Outputs 500m shielded / 150m unshielded
Dimensions (W x H x D) 45mm x 100mm x 75mm

Full technical specifications are available on the product page at LeadTime.ca.

SM 1223 vs SM 1224 vs SM 1231 vs Remote I/O: Which One Does Your Project Actually Need?

Characteristic SM 1223 (6ES7223-1BH32-0XB0) SM 1224 SM 1231 Remote I/O ET 200
Input Points 8 digital, 24V DC 8 digital, 24V DC 8 digital or analog mixed Configurable, 16+
Output Points 8 transistor, 0.5A 8 relay contacts 0 (input-only) Configurable, 16+
Output Current Per Channel 0.5A Higher (relay contact) N/A Configurable
Output Isolation Transistor, 500V AC to backplane Relay N.O. contacts N/A Depends on config
Mounting Location CPU side, cabinet CPU side, cabinet CPU side, cabinet Field / distributed
External Protection Required Yes — fuses mandatory Relay provides internal protection Yes — fuses required Depends on configuration
Relative Module Cost Low Medium-High Medium High
Typical Lead Time 1–2 weeks 1–2 weeks 1–2 weeks 2–4 weeks
Best For Digital switches, solenoids, small loads Isolation, high current per point Analog sensors: temp, pressure, flow Distributed systems, large I/O count

If your architecture uses transistor-compatible loads within the 0.5A-per-channel limit, the 6ES7223-1BH32-0XB0 is the correct and most cost-effective choice — check current availability at LeadTime.ca.

Expert Verdict: When to Order the 6ES7223-1BH32-0XB0 and When to Look Elsewhere

The Siemens 6ES7223-1BH32-0XB0 consistently delivers on its core promise: the most compact and cost-effective way to add 8 digital inputs and 8 transistor outputs to an existing S7-1200 system. Its sink/source input flexibility removes the field wiring headache of matching sensor polarity, and the selectable input delay from 0.2ms to 12.8ms gives engineers genuine noise control without external filtering components. For solenoid valves, motor contactors via small relays, indicator lamps, and digital sensor inputs — which describes the majority of discrete manufacturing I/O tasks — this module covers the workload at a module cost well below the SM 1224 relay alternative.

The honest limits are equally important to state. The 0.5A-per-channel transistor output is a real constraint. If any single load draws more than 0.5A, or if the application requires galvanic isolation between control and load circuits — motor starters, safety circuits, or mixed-voltage loads — the SM 1224 is the correct choice and no amount of external fusing changes that. Similarly, if any signal in your system is analog — thermocouple, 4-20mA loop, 0-10V speed reference — the SM 1223 cannot be substituted for SM 1231 or SM 1232. Attempting to force an analog signal into a digital input will not work and risks module damage. The external short-circuit protection requirement also adds a small but real cost to the total BOM that engineers sometimes omit from initial budget estimates — budget for fuses or overload relays on every output group before you close your panel design.

From a procurement standpoint, the 6ES7223-1BH32-0XB0 is an active product in continuous production with typical distributor lead times of 1 to 2 weeks for stock items. Its position in the S7-1200 portfolio makes it one of the more reliably available S7-1200 signal modules globally. Volume pricing is available for OEM builds that standardize on this module across a product family — a common practice for machine builders who want to reduce spare parts complexity. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

The following points cover the key requirements and configurations engineers must verify before and during installation. For complete wiring diagrams and step-by-step procedures, refer to the official Siemens SM 1223 installation manual included with the module.

  • The SM 1223 snaps onto the right side of the S7-1200 CPU via the integrated backplane connector — power off the CPU and disconnect the 24V DC supply before mounting or dismounting the module
  • Inputs accept 24V DC in both sink (NPN field device) and source (PNP field device) configurations — verify polarity matches your field device type before terminating cables
  • Use shielded cable for any input run exceeding 300m or any output run exceeding 150m; ground the shield at the controller end only to avoid ground loops
  • External fuses or thermal overload relays are mandatory on every output group before commissioning — the SM 1223 has no built-in short-circuit protection, and an unprotected short will damage the module and connected field wiring
  • After physical installation, add the module in STEP 7 TIA Portal device configuration using catalog number 6ES7223-1BH32-0XB0, confirm TIA Portal v12 or later is in use, and set input delay values per input group based on the noise characteristics of your field environment

Compatible Modules and System Expansion Within the S7-1200 Family

The 6ES7223-1BH32-0XB0 is part of the SIMATIC S7-1200 signal module family and can be combined with other S7-1200 signal modules on the same CPU backplane, subject to the expansion limits of your specific CPU model. The following modules are commonly deployed alongside or instead of the SM 1223 within the same platform:

  • SM 1221 — Digital input-only expansion module for applications that need additional inputs without outputs
  • SM 1222 — Digital output-only expansion module when additional output channels are needed without adding inputs
  • SM 1224 — Digital I/O module with relay contacts instead of transistor outputs, for higher current or isolated switching applications
  • SM 1231 — Analog input module for temperature, pressure, and flow signals using thermocouple, RTD, 4-20mA, or 0-10V sensors
  • SM 1232 — Analog output module for variable speed drives, control valves, and other analog-commanded actuators

Wrong-Part Prevention Checklist Before You Order

Run through every item on this checklist before placing your order. Each point corresponds to a real failure mode documented in field installations of the SM 1223:

  1. Verify your CPU is S7-1200 compatible (not S7-1500, S7-300, etc.)
  2. Confirm 24V DC power is available and stable (20.4-28.8V acceptable range)
  3. Check that all connected field devices are 24V DC rated
  4. Verify that any output load does not exceed 0.5A per channel or 4A total per output group
  5. Ensure cable runs are within 500m shielded or 300m unshielded limits
  6. Confirm no short-circuit protection is built into SM 1223 (external fuses or contactor protection required)
  7. Verify mounting space on the right side of CPU (dimensions 45mm W x 100mm H x 75mm D)
  8. Check that your STEP 7 TIA Portal software version supports parameterizing input delays

If any item on this checklist raises a question before you order, contact the LeadTime.ca team — or review the full product details page to confirm part suitability for your application.

Frequently Asked Questions

Does the SM 1223 include short-circuit protection on the outputs?

No. The 6ES7223-1BH32-0XB0 does not include any integrated short-circuit protection on its transistor outputs. External fuses or thermal overload relays must be installed on every output group before commissioning. Operating the module without external protection after a wiring short will damage the transistor output stage and require module replacement.

Can the SM 1223 replace the SM 1224 if I need higher output current?

No. The SM 1223 transistor outputs are rated at 0.5A per channel maximum, with 4A total per output group. The SM 1224 uses relay contacts capable of higher current per point. If your load draws more than 0.5A per channel, the SM 1223 is not an acceptable substitute — use the SM 1224 or add an external relay driven by the SM 1223 output.

What input delay settings are available, and how do I configure them?

Input delay is selectable at 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, or 12.8 ms per input group. Configuration is done in STEP 7 TIA Portal through the module's Properties panel under the Input tab. Faster settings improve response time but may pass electrical noise as valid signals; slower settings filter noise but reduce input response speed. TIA Portal v12 or later is required to access these parameters.

What is the maximum cable length for SM 1223 outputs, and does shielding matter?

Output cable runs are limited to 500m with shielded cable and 150m with unshielded cable. In electrically noisy factory environments — near variable frequency drives, large motors, or high-current switching equipment — shielded cable grounded at the controller end is strongly recommended for any output run, regardless of length.

How many SM 1223 modules can I connect to one S7-1200 CPU?

The maximum number of signal modules that can be connected depends on the specific S7-1200 CPU model in your system. Different CPU variants support different maximum expansion counts. Verify your CPU's expansion limit in the STEP 7 TIA Portal device catalog or the CPU's technical data sheet before ordering multiple SM 1223 units for a single controller.

Is the 6ES7223-1BH32-0XB0 suitable for washdown or food-grade enclosures?

No. The SM 1223 carries an IP20 protection rating, which provides basic protection against contact with internal components but no protection against water, liquids, or dust ingress. The module requires installation inside a sealed control cabinet. For washdown or wet environments, use an appropriately rated enclosure with the cabinet achieving the necessary IP rating for the application.

Why Engineers and Procurement Teams Order From LeadTime.ca

  • LeadTime.ca ships the Siemens 6ES7223-1BH32-0XB0 worldwide — not limited to any single region or country
  • Hard-to-find and short-lead-time S7-1200 signal modules are sourced through verified supply channels
  • Volume pricing is available for OEM builds and system integrators standardizing on a module across multiple machines
  • The LeadTime.ca team can confirm real stock levels and lead times before you commit to a build schedule
  • Both technical and procurement questions are answered directly — not routed through automated systems

At-a-Glance Summary

  • Module: Siemens 6ES7223-1BH32-0XB0, SIMATIC S7-1200 Digital I/O SM 1223
  • I/O count: 8 digital inputs, 24V DC, sink/source; 8 digital outputs, transistor, 0.5A per channel
  • Supply voltage range: 20.4 to 28.8V DC; power consumption 2.5W
  • Input delay selectable: 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, or 12.8 ms per group
  • Output delay: 50µs to 200µs; total output current per group: 4A
  • Dimensions: 45mm W x 100mm H x 75mm D; weight 210g
  • IP20 rated — requires cabinet mounting; operating temperature -20 to 60°C horizontal, -20 to 50°C vertical
  • No built-in short-circuit protection — external fuses mandatory on all output groups
  • Cable limits: outputs 500m shielded / 150m unshielded; inputs 500m shielded / 300m unshielded
  • Typical distributor lead time: 1–2 weeks; active product in continuous production
  • Certifications: CE, IEC 61131-2, UL and CUL available through Siemens North America documentation