Product Overview

The Schneider Electric SR2A201FU is a Zelio Logic compact smart relay for small and medium-sized machine-control applications. It operates from a 100–240 V AC supply and combines 12 discrete inputs, eight relay outputs, programmable logic, and an integrated display. With 20 onboard I/O points, it offers more input and output capacity than the 10-I/O SR2A101FU while retaining the same general approach to standalone automation.

The SR2A201FU is intended for applications where conventional relays, timers, and auxiliary contacts would otherwise be used to implement a sequence. Instead of wiring every control relationship through separate components, the user can program the required conditions and output actions in the smart relay. This simplifies the logic for suitable machines and makes subsequent sequence changes easier to manage.

Its 12 digital inputs accept compatible AC field signals. These can include operator push buttons, limit switches, auxiliary contacts, and other devices that provide discrete states within the specified input range. The eight relay outputs switch compatible external control circuits, allowing the relay to operate contactor coils, interface relays, indicator circuits, and other loads within their permitted electrical ratings.

For example, a small material-handling system may use several sensors to detect product position, switches to monitor mechanical travel, and relay outputs to control conveyor contactors and warning indicators. The SR2A201FU can process these signals and coordinate the operating sequence without requiring a larger PLC for an application of this scale.

The integrated LCD and navigation buttons provide a local interface for viewing supported information and accessing device functions. Programming is supported through Zelio Soft, with ladder logic and function block diagram programming available for the applicable functions. Ladder logic is particularly convenient for technicians familiar with relay-based control diagrams, while function block diagrams can help organize more involved logic sequences.

The eight relay outputs provide greater switching-channel capacity than the four-output SR2A101FU. This is useful when a machine has several independently controlled devices, although the available output count does not eliminate the need to consider the electrical ratings of individual contacts and output groups. Load current, inrush, switching frequency, and the characteristics of inductive loads all influence the appropriate output arrangement.

The SR2A201FU does not include a real-time clock. Its program can evaluate input states and supported internal logic functions, but built-in calendar-based scheduling is not available. Applications requiring a clock for daily or weekly schedules need a suitable external timing arrangement or a smart relay model with the required clock functionality.

The controller also uses EEPROM memory to retain its program for up to ten years at the specified reference temperature of 25°C. This helps preserve the application during a loss of supply, although a separate copy of the approved program remains useful for maintenance and replacement work.

The SR2A201FU is suited to control panels where AC-powered inputs, multiple relay outputs, and locally accessible programmable logic are required. Its 20-I/O configuration provides a practical middle ground between a small smart relay and a larger controller, provided the application does not require unsupported analog, high-speed, or advanced communication functions.

Technical Specifications

Product Features

• 20 onboard I/O points: Combines 12 digital inputs and eight relay outputs for applications requiring multiple control signals.
• 100–240 V AC power supply: Fits automation panels built around an AC-powered control arrangement.
• AC digital inputs: Accepts compatible field signals from switches, auxiliary contacts, and other discrete devices.
• Eight relay outputs: Provides switching channels for compatible control circuits and external switching equipment.
• Integrated LCD interface: Supports local viewing and access to available device functions.
• Ladder logic programming: Allows control sequences to be developed using a familiar relay-logic representation.
• Function block diagram programming: Provides an alternative method for organizing supported control functions.
• EEPROM program retention: Preserves the stored program for up to ten years at the specified reference temperature.
• No built-in real-time clock: Suits applications that do not depend on calendar-based scheduling.
• Standalone machine control: Combines programmable logic and relay switching in one device.

Working Principle

The SR2A201FU monitors its 12 digital inputs, evaluates the programmed control logic, and operates its eight relay outputs according to the resulting conditions.

100–240 V AC Supply → SR2A201FU → Program Execution → Relay Outputs → External Control Circuits

The input circuits receive signals from compatible AC field devices. For instance, a limit switch may indicate that a machine component has reached its end position, while an auxiliary contact reports whether a contactor is energized. The controller reads these input states and makes them available to the application program.

The program defines how those states affect machine operation. A conveyor sequence might require a start command, confirmation that a guard interlock is satisfied, and a valid downstream condition before energizing the conveyor output. Other logic can handle stop commands, operating-state changes, and alarm indications using the functions supported by the controller.

Ladder logic expresses these conditions through contacts, coils, and supported logic elements. Function block diagram programming uses connected functional blocks to represent the required operations. Both approaches can be used to implement straightforward machine sequences, with the choice depending on the programmer’s preferred method and the complexity of the application.

When an output condition becomes true, the corresponding relay output changes state and switches its connected circuit. For example, an output may energize a contactor coil, which then controls a motor power circuit. The smart relay is a control device rather than a substitute for motor power switching, branch-circuit protection, or required safety equipment.

The eight relay outputs give the SR2A201FU more direct control channels than a four-output model. However, output wiring must account for the contact ratings and the current permitted through each common terminal. The total output thermal-current limit also applies, so the maximum current of an individual contact must not be confused with the permissible combined load across all outputs.

The 100–240 V AC input arrangement requires compatible field-device voltages and suitable wiring practices. Technicians should not assume that these inputs can be connected directly to 24 V DC sensors. Where a machine uses low-voltage DC field devices, suitable interface equipment or a smart relay with matching input specifications may be necessary.

The integrated display provides a local interface for supported monitoring and device operations. Zelio Soft can be used to develop and transfer the control program. During commissioning, the input states, program conditions, and relay output responses should be tested against the actual machine sequence.

EEPROM memory retains the program during a power interruption under the specified conditions. After supply power returns, the controller’s behavior depends on its configuration and the external circuit states. The machine should be arranged so that power restoration does not cause an unintended movement or hazardous restart.

Because the SR2A201FU has no real-time clock, its built-in functions do not provide calendar-based daily or weekly scheduling. If the control sequence depends on a specific time of day, the application requires an external timing solution or a model with the necessary clock capability.

When an output fails to operate, the diagnosis should distinguish between an unmet program condition, incorrect channel assignment, a supply problem, and a fault in the external circuit. Checking input status, program logic, output state, and connected load separately helps identify the cause without unnecessary component replacement.

Role in the Industrial Control Architecture

The SR2A201FU serves as a standalone programmable controller between field input devices and external control circuits. Its 12 inputs collect machine states, while its eight relay outputs switch compatible loads according to the stored program.

AC Field Devices → SR2A201FU → Relay Outputs → Contactors and Control Loads

The smart relay executes the machine sequence, while external switching equipment handles loads that require separate power circuits. The overall design must account for input voltage, relay contact ratings, electrical protection, and the required machine safety functions.

Industrial Applications

Installation and Maintenance

1. Verify the model reference: Confirm that the device is SR2A201FU and that its 20-I/O configuration suits the intended application.
2. Prepare the control enclosure: Provide suitable mounting, wiring access, and environmental conditions for the smart relay.
3. Install the controller: Use a compatible 35 mm DIN rail or the supported screw-fixing arrangement.
4. Check the AC supply: Verify that the supply voltage and frequency are within the specified operating limits.
5. Identify the input channels: Label the 12 input circuits and confirm that connected field signals match the AC input requirements.
6. Wire the relay outputs: Follow the terminal diagram and observe the permitted contact and common-terminal current limits.
7. Review connected loads: Check voltage, current, inrush, and inductive characteristics before assigning loads to relay outputs.
8. Develop the control program: Implement the required operating sequence using supported ladder logic or function block diagram programming.
9. Test the input logic: Operate each field device and confirm that the controller recognizes the expected input state.
10. Verify output responses: Test each relay output against the programmed sequence and inspect the operation of the connected control equipment.
11. Check power-restoration behavior: Confirm that the machine responds as intended after interruption and restoration of the AC supply.
12. Maintain program and wiring records: Keep a verified copy of the program, I/O assignments, wiring diagrams, and commissioning results.

If the controller does not detect an input, check the field signal voltage, terminal wiring, and input assignment. If an output does not operate, inspect the program conditions, output state, external supply, and connected load. Isolate the appropriate electrical supply before performing wiring or maintenance work.

Related Components

Recommended Related Models

Key Advantages

• Provides 12 AC digital inputs and eight relay outputs in one compact controller.
• Operates from a 100–240 V AC supply.
• Offers more I/O points than the 10-I/O SR2A101FU.
• Includes an integrated LCD interface for local access.
• Supports ladder logic and function block diagram programming.
• Retains the stored program in EEPROM under the specified conditions.
• Suits small automation systems requiring multiple relay-controlled circuits.

Technical FAQs

How does the SR2A201FU differ from the SR2A101FU?

The SR2A201FU provides 20 I/O points, comprising 12 inputs and eight relay outputs. The SR2A101FU provides 10 I/O points, comprising six inputs and four relay outputs. Both use a 100–240 V AC supply, have an integrated display, and do not include a real-time clock.

Can all eight relay outputs operate at their individual maximum currents simultaneously?

No. The permissible load must account for both the individual output ratings and the total thermal-current limit across the outputs. The SR2A201FU has a specified total relay output thermal current of 8 A across all eight outputs. The actual load arrangement must also respect the limits of the relevant contacts and common terminals.

Is the SR2A201FU suitable for 24 V DC proximity sensors?

Its onboard digital inputs are specified for 100–240 V AC signals, so a typical 24 V DC sensor should not be connected directly as though the inputs were DC-rated. A suitable interface arrangement or a smart relay with compatible DC inputs is needed for that type of field device.

What should be considered when choosing between SR2A201FU and SR2B201FU?

Both models provide 20 I/O points and use a 100–240 V AC supply. The SR2A201FU does not include a real-time clock, while the SR2B201FU includes one. The choice depends on whether the application requires calendar-based scheduling in addition to ordinary input-driven control logic.