X20SO4120 B&R X20 Series 4-Channel High-Current Safe Output Module

Product Overview

The X20SO4120 (X20SO4120) is a high-performance, intelligent safety output module designed for the B&R X20 system. Engineered to meet the most stringent safety requirements (up to SIL 3 / PLe), this module features 4 safe digital Type A outputs, each capable of delivering up to 2 A of current. This high-current capacity makes the X20SO4120 ideal for directly driving larger safety actuators, heavy-duty contactors, and hydraulic valves without the need for interposing relays. With integrated OSSD (Output Signal Switching Device) functionality and a diagnostic pulse width of less than 500 microseconds, the module ensures continuous monitoring for short circuits and cross-faults, maintaining maximum safety integrity in high-speed automated environments such as metal forming, robotic cells, and heavy material handling.

Technical Configuration

The hardware of the X20SO4120 is built for transparency and resilience. It features individual current monitoring for each channel, allowing the Safety CPU to detect "stuck-at" faults or load anomalies in real-time. The module identifies itself in the system via the B&R ID code 0x2007 and provides comprehensive visual diagnostics through LEDs indicating I/O function per channel, operating state, and general module status. Power management is highly efficient, with a bus consumption of just 0.25 W, while the internal I/O circuitry draws 1.3 W. By utilizing the openSAFETY protocol, the X20SO4120 provides a seamless, deterministic safety loop that minimizes the time between a fault detection and the transition to a Safe State.

Technical Specifications

Technical FAQs

How does the 2 A rating of the X20SO4120 compare to the X20SO4110?

The X20SO4120 provides a significantly higher output capacity (2 A per channel) compared to the X20SO4110 (0.5 A). This allows the 4120 variant to drive high-power inductive loads like large DC brakes or pneumatic manifolds directly, which would otherwise exceed the current limits of standard safe output modules.

What diagnostics are available via the status indicators?

The module features LEDs for "Operating State" and "Module Status," which indicate if the module is in safe-run mode, pre-operational mode, or a fail-safe state. Additionally, individual "I/O function" LEDs light up when an output is energized, and flash patterns can indicate specific faults like short circuits or overcurrent.

Is the OSSD pulse width adjustable?

The <500 microsecond pulse width is a fixed hardware characteristic designed to ensure that the "off-test" is too fast for the mechanical contacts of a relay or valve to respond, thus preventing chattering while maintaining a high diagnostic coverage.

Engineering & Installation Guide

• Total Current Calculations: With a 2 A capacity per channel, a fully loaded module can draw up to 8 A. It is critical to ensure that the X20 power supply module (e.g., X20PS) feeding this segment is rated for the cumulative peak current and that the supply wiring is of sufficient gauge to prevent voltage drops during simultaneous switching.

• Inductive Load Protection: When controlling large inductive loads, the back-EMF can be substantial. Although the X20SO4120 has internal protection, adding an external recovery diode or varistor at the load side is recommended for 2 A applications to reduce electromagnetic noise and thermal stress on the module’s transistors.

• Safe Wiring separation: To maintain the SIL 3 rating, keep the safe output wiring physically separated from high-voltage AC cables. Use shielded cables for the 24 VDC lines if they run parallel to motor cables for long distances to prevent induced voltages from interfering with the OSSD pulse detection logic.