Product Overview

The Siemens 6AG2223-1PL32-1XB0 SIPLUS S7-1200 Digital I/O Module is an SM 1223 combined digital input/output module developed for railway-related automation applications. It provides 16 digital inputs operating at 24 V DC and 16 relay outputs rated at 2 A per output, allowing a single module to handle both signal acquisition and switching tasks.

This module is based on the standard 6ES7223-1PL32-0XB0 SM 1223 hardware configuration but incorporates SIPLUS extreme RAIL features, including conformal coating and environmental qualification for railway applications. It is intended for installations where ordinary industrial I/O modules may not meet the required environmental and railway operating conditions.

The 16 digital inputs accept 24 V DC signals from field devices such as limit switches, proximity sensors, pushbuttons, and equipment status contacts. The 16 relay outputs can switch external loads, including contactor coils, indicator circuits, and other control devices within their electrical ratings.

A typical application is a railway auxiliary control cabinet. The input channels can collect operating signals from door-position switches, equipment interlocks, compartment monitoring contacts, and auxiliary system sensors. Meanwhile, the relay outputs can control ventilation contactors, warning indicators, auxiliary relays, and other switching circuits.

The relay output configuration is particularly useful when the controlled equipment requires contact-based switching rather than transistor outputs. The module supports output voltages from 5 to 30 V DC and 5 to 250 V AC, subject to the specified load and switching ratings.

Another distinguishing feature is its conformal coating. Railway electrical equipment may encounter condensation, temperature fluctuations, dust, oil droplets, and chemically active substances. The protective coating helps protect the printed circuit assemblies against environmental contamination.

The module is rated for an operating temperature range of -25 to +60 °C, with operation at +70 °C permitted for 10 minutes under the specified OT1 and ST1/ST2 conditions. It also meets relevant railway requirements, including EN 50155, EN 50121-3-2, and EN 61373.

For control engineers, the main selection consideration is the combination of 16 digital inputs and 16 relay outputs. It is particularly useful when a railway control system needs a relatively high number of discrete signals without installing separate input and output modules.

Technical Specifications

Product Features

• 16 Digital Inputs: Acquires 24 V DC signals from switches, sensors, and equipment status contacts.
• 16 Relay Outputs: Provides contact-based switching for external control circuits.
• 2 A Switching Capacity: Supports resistive loads up to 2 A per relay output under specified conditions.
• AC and DC Switching: Supports output voltages from 5–250 V AC and 5–30 V DC.
• SIPLUS Conformal Coating: Protects electronic assemblies against environmental contamination.
• Railway Environmental Qualification: Supports applications subject to EN 50155 railway requirements.
• Wide Temperature Capability: Operates from -25 to +60 °C, with specified short-term operation at +70 °C.
• Configurable Input Delay: Offers selectable input delay settings from 0.2 to 12.8 ms.
• Diagnostic Monitoring: Supports supply voltage monitoring, diagnostic alarms, and input/output status indication.
• Electrical Separation: Relay outputs provide channel separation, while digital input potential separation is arranged in groups of two.

Working Principle

The 6AG2223-1PL32-1XB0 combines two different functions within one SM 1223 module: converting external 24 V DC signals into PLC-readable input states and switching external loads through relay contacts.

Its signal flow can be divided into two paths:

Digital Input Path:

Field Switches / Sensors → Digital Input Circuit → Signal Processing → S7-1200 Backplane → CPU

Digital Output Path:

S7-1200 CPU → Output Control Circuit → Relay Coil → Relay Contacts → External Load

On the input side, field devices generate discrete signals according to the operating condition of the equipment. For example, a door-position switch may change its output state when a railway vehicle door reaches its fully closed position.

The module receives the 24 V DC signal through the assigned input terminal. Its input circuitry evaluates the voltage level and converts the external electrical condition into an internal digital state. The controller can then use this information for interlocking, status monitoring, and alarm logic.

The input delay can be configured between 0.2 and 12.8 ms. This allows the control system to adjust how quickly input transitions are recognized, which can be useful when dealing with contact bounce or short electrical disturbances.

On the output side, the S7-1200 CPU determines when a relay should operate according to the user program. When an output is activated, the corresponding relay coil is energized and its contacts change state, switching the connected external circuit.

For example, a railway auxiliary ventilation system may use several digital inputs to monitor equipment status and temperature-related control conditions. Based on the programmed logic, the PLC activates selected relay outputs to operate ventilation contactors or issue warning signals.

The relay contacts support both AC and DC switching within their specified voltage and current ratings. This makes the module suitable for different types of auxiliary control circuits, although the actual load type, inrush current, and switching frequency must be considered during circuit design.

The combination of input acquisition and relay switching allows the controller to manage equipment status and discrete control commands through one compact I/O module.

Role in the SIPLUS S7-1200 Control Architecture

The 6AG2223-1PL32-1XB0 operates as an expansion signal module in an S7-1200 automation system. It increases the number of available digital input and relay output channels beyond the integral I/O provided by the CPU.

A typical control arrangement follows this structure:

Field Sensors and Switches → SM 1223 Digital Inputs → S7-1200 CPU → SM 1223 Relay Outputs → External Control Equipment

The module’s relay outputs are particularly useful when external circuits require potential separation or when different load voltages are used. Each relay output provides contact-based switching, rather than the fixed electronic output arrangement found in transistor modules.

The 16 digital inputs are arranged in groups of two for potential separation. The relay outputs also provide separation between individual channels, with output separation arranged in groups of four in the specified architecture.

The SIPLUS version adds environmental protection and railway qualification to the underlying SM 1223 functionality. This makes it relevant to rolling-stock control cabinets and other railway electrical installations where temperature, vibration, and contamination requirements must be considered.

Industrial Applications

Installation and Maintenance

1. Verify the Module Configuration: Confirm that 6AG2223-1PL32-1XB0 is the required 16DI/16DQ relay version and that the application needs both 24 V DC inputs and relay outputs.
2. Check the Installation Environment: Review the ambient temperature, vibration, condensation, and contamination conditions against the module’s SIPLUS railway specifications.
3. Inspect the Mounting Position: Check the S7-1200 mounting arrangement and ensure that sufficient space is available for the module and its wiring.
4. Isolate the Power Supply: Disconnect the relevant supply circuits according to the site’s electrical safety and lockout procedures before installation or wiring work.
5. Inspect the Module: Check the housing, front connector, and terminal areas for physical damage or contamination.
6. Install the Module: Mount the SM 1223 module in the designated S7-1200 expansion position and secure it according to the system installation instructions.
7. Wire the Digital Inputs: Connect the 16 field input signals according to the assigned terminal numbers and the required sink/source configuration.
8. Connect the Relay Outputs: Wire the external loads to the corresponding relay contacts. Check the selected AC or DC voltage and ensure that the load current remains within the specified ratings.
9. Check External Protection: Provide appropriate external short-circuit and overcurrent protection. The relay outputs do not have integrated short-circuit protection.
10. Configure the Input Parameters: Set the required input delay values according to the connected field devices and the response requirements of the control program.
11. Perform Functional Testing: Restore power and test each input and output channel individually. Confirm that the PLC reads the correct input states and that the relay contacts operate as expected.
12. Record the Installation Details: Document the I/O assignments, external supply circuits, relay loads, protective devices, and module diagnostic information for future maintenance.

Compatible System Components

Recommended Related Models

Key Advantages

• Combines 16 digital inputs and 16 relay outputs in one module.
• Supports 24 V DC digital input signals.
• Provides 16 relay contacts rated up to 2 A.
• Supports both AC and DC output switching.
• Incorporates conformal coating for environmental protection.
• Qualified for relevant railway operating conditions.
• Supports configurable digital input delays.
• Provides input/output status indication and diagnostic monitoring.
• Suitable for compact S7-1200 railway control installations.

Technical FAQs

What is the difference between Siemens 6AG2223-1PL32-1XB0 and 6ES7223-1PL32-0XB0?

The 6AG2223-1PL32-1XB0 is the SIPLUS extreme RAIL version based on the standard 6ES7223-1PL32-0XB0. Both provide 16 digital inputs and 16 relay outputs, but the SIPLUS version adds conformal coating and railway environmental qualification, including relevant temperature, vibration, and EMC requirements.

Can the relay outputs of the 6AG2223-1PL32-1XB0 switch AC loads?

Yes. The relay contacts support output voltages from 5 to 250 V AC, as well as 5 to 30 V DC. The maximum rated switching current is 2 A under the specified load conditions. The actual load type and switching characteristics must be checked before connecting equipment.

Does the module have built-in short-circuit protection for its relay outputs?

No. The relay outputs do not have integrated short-circuit protection. External protective devices must be provided according to the connected circuit, load characteristics, and applicable electrical installation requirements.

What environmental conditions should be considered when installing this SIPLUS module?

The module supports an operating temperature range of -25 to +60 °C, with +70 °C permitted for 10 minutes under specified railway temperature classes. Installation planning should also consider condensation, vibration, shock, dust, and chemically active substances. The conformal coating provides additional protection for the electronic assemblies, but it does not replace correct enclosure selection or installation practices.