BECKHOFF EL1258 8-Channel Multi-Timestamp Digital Input Terminal

Product Overview

The EL1258 (EL1258) is a high-performance 8-channel digital input terminal designed for ultra-fast signal acquisition within the EtherCAT I/O system. Engineered for applications requiring extreme temporal precision—such as high-speed part detection, print mark registration, and synchronized motion triggers—the EL1258 features a remarkable input filter of less than 1 µs. By utilizing Distributed Clocks (DC) and advanced multi-timestamping technology, this terminal can detect and log multiple signal edges within a single EtherCAT cycle. This allows the controller to reconstruct high-frequency events with a precision of much less than 1 microsecond, effectively overcoming the limitations of the fieldbus cycle time.

Technical Configuration

The hardware architecture of the EL1258 is housed in a High-Density (HD) 12 mm casing, supporting 8 digital inputs with 2-wire connection technology. It is compliant with IEC 61131-2 (Type 1/3) standards, ensuring compatibility with standard 24 VDC industrial sensors. The "Multi-Timestamp" feature is the core technical advantage: it enables the terminal to store up to 32 timestamps per channel (depending on configuration), allowing the PLC to process events that occur faster than the task cycle. The module provides 500 V electrical isolation between the E-bus and the field potential and is powered via the EtherCAT strand, consuming typically 130 mA from the E-bus.

Technical Specifications

Technical FAQs

What is the benefit of multi-timestamping over standard digital inputs?

Standard digital inputs can only report the state of a signal at the moment the EtherCAT cycle reaches them. If a signal toggles multiple times between cycles, those events are lost. The EL1258 records the exact time (timestamp) of every edge transition, allowing the PLC to know exactly when multiple events occurred, even if they happened in the middle of a communication cycle.

Does this terminal support Distributed Clocks?

Yes. The EL1258 relies on Distributed Clocks (DC) to synchronize its internal high-speed clock with the rest of the EtherCAT network. This is what allows the timestamps to be globally valid across the entire control system.

How many edges can the EL1258 detect per second?

Depending on the configuration and the required buffer size, it can detect between 25,000 and 100,000 edges per second. This makes it suitable for high-speed pulse counting and rotation monitoring beyond the capabilities of standard I/O.

Engineering & Installation Guide

• High-Density Wiring: Because the EL1258 uses an HD housing, space is limited. Use ferrules for stranded conductors (0.14 to 0.75 mm²) to ensure clean, reliable connections and prevent stray wire strands from causing short circuits between the closely packed input points.

• Signal Quality for < 1 µs Filtering: Since the input filter is extremely fast (< 1 µs), the terminal is sensitive to very short noise spikes. Always use shielded cabling for high-speed signals and route them away from high-power AC cables or VFD leads. Use high-quality sensors with clean switching characteristics to avoid false "double-triggering."

• Software Configuration: In TwinCAT, you must enable the DC (Distributed Clocks) mode for the EL1258. You will also need to configure the "Number of Timestamps" in the CoE (CanOpen over EtherCAT) settings to match your application's requirements; increasing the buffer size may increase the process image size.

• Stripping and Installation: Strip wires to exactly 8–9 mm. Use a flat-head screwdriver to actuate the spring terminals. Ensure the terminal is securely locked onto the DIN rail to maintain a stable connection to the E-bus power contacts.