EL1252

Product information

Product Overview

The EL1252 is a 2-channel 24 V DC digital input terminal that records when an edge happened, not merely that it happened. Each channel carries a hardware timestamp with a resolution of 1 ns and an accuracy of 10 ns between channels, plus an input delay below 1 µs and the ability to latch the last edge.

It exists for applications where sequence matters at a resolution the PLC cycle cannot express: flying shears, registration on a moving web, positional triggering, and fault diagnosis where you need to know which of two signals actually arrived first.

Why Buyers Specify This Model

Timestamps beat fast scanning

A conventional input terminal tells the controller the state of a signal at the moment it is read. If two events happen within one PLC cycle, the controller cannot tell them apart. The EL1252 stamps each edge with a 1 ns-resolution time, so the sequence is preserved even when both events land in the same cycle.

The cross-channel accuracy of 10 ns plus input delay is what makes it useful for comparing two signals: a door sensor against a drive enable, an overtravel switch against a stop command, a registration mark against an axis position.

Distributed Clocks for system-wide correlation

The terminal supports Distributed Clocks with an accuracy far below 1 µs. That means its timestamps can be correlated with timestamps from other DC-capable terminals and with the axis positions of a motion controller — not just compared against each other inside one module.

This is the mechanism that lets a measuring station or a cam-driven machine reconstruct a precise timeline across the whole system rather than per device.

Latching and the process image

The special features Beckhoff publishes for the EL1252 are timestamp and latch last edge. The latch function captures an edge that would otherwise be gone before the controller read it — essential for single-shot events such as a once-per-stroke trigger.

The process image is 2 input bits plus 2 × 16 bytes of timestamp data, and the terminal draws typically 110 mA from the E-bus. It is a 4-wire connection, unlike the simpler 1-wire EL1008.

Technical Specifications (Official Beckhoff Data)

Parameter	Official value
Connection technology	4-wire
Specification	similar to EN 61131-2, type 3, “0”: -3…5 V DC, “1”: 11…30 V DC, typ. 3 mA input current
Number of inputs	2
Nominal voltage	24 V DC (-15%/+20%)
Signal voltage “0”	-3…+5 V (similar to EN 61131-2, type 3)
Signal voltage “1”	11…30 V (similar to EN 61131-2, type 3)
Input current	typ. 3 mA (similar to EN 61131-2, type 3)
Input filter	typ. < 1 µs
Timestamp resolution	1 ns
Timestamp accuracy	10 ns (+ input delay) between the channels
Input delay T ON /T OFF	< 1 µs
Distributed clocks	yes
Distributed clock accuracy	<< 1 µs
Time resolution signal	1 ns
Current consumption power contacts	–
Current consumption E-bus	typ. 110 mA
Electrical isolation	500 V (E-bus/field potential)
Bit width in the process image	2 x input + 2 x 16 byte timestamp
Configuration	no address or configuration setting
Special features	timestamp, latch last edge
Weight	approx. 55 g
Operating temperature	-25…+60°C
Storage temperature	-40…+85°C
Relative humidity	95%, no condensation
Vibration/shock resistance	conforms to EN 60068-2-6/EN 60068-2-27
EMC immunity/emission	conforms to EN 61000-6-2/EN 61000-6-4
Protect. rating/installation pos.	IP20/variable
Pluggable wiring level	for all ESxxxx terminals
Approvals/markings	CE, CCC, UL, ATEX, IECEx, cFMus
Ex marking	ATEX: / II 3G Ex ec IIC T4 Gc / IECEx: / Ex ec IIC T4 Gc / cFMus: / Class I, Division 2, Groups A, B, C, D / Class I, Zone 2, AEx ec IIC T4 Gc

Specifications are Beckhoff’s official product data for the EL1252. The ES1252 variant is identical but with a pluggable wiring level.

Housing, Installation and Wiring

Data	Official value
Design form	compact terminal housing with signal LEDs
Material	polycarbonate
Installation	on 35 mm DIN rail, conforming to EN 60715 with lock
Side by side mounting by means of	double slot and key connection
Marking	labeling of the BZxxxx series
Wiring	solid conductor (s), flexible conductor (st) and ferrule (f): spring actuation by screwdriver
Connection cross-section	s*: 0.08…2.5 mm², / st*: 0.08…2.5 mm², / f*: 0.14…1.5 mm²
Connection cross-section AWG	s*: AWG28…14, / st*: AWG28…14, / f*: AWG26…16
Stripping length	8…9 mm
Current load power contacts	I max : 10 A
Dimensions (W x H x D)	12 mm x 100 mm x 68 mm

Ordering Information and Variants

Beckhoff’s own ordering information for this product:

Order code	Official description
EL1252	EtherCAT Terminal, 2-channel digital input, 24 V DC, 1 µs, timestamp
ES1252	EtherCAT Terminal, 2-channel digital input, 24 V DC, 1 µs, timestamp, pluggable wiring level
EL1252-0010	EtherCAT Terminal, 2-channel digital input, 24 V DC, 10 µs, timestamp
EL1252-0050	EtherCAT Terminal, 2-channel digital input, 5 V DC, 1 µs, timestamp

Material Compliance

The following is Beckhoff’s published material compliance data for this product, reproduced unchanged. Beckhoff notes that absence of a substance is not verified by analytical tests.

Item	Official statement
REACH SVHC	no
POP	compliant
RoHS	compliant with exemption
RoHS exemption	7c-I: Lead-containing electrical and electronic components in glass and ceramic materials, excluding dielectric ceramics in capacitors
China-RoHS	www.beckhoff.com/china-rohs-io
CA Prop65	www.beckhoff.com/prop65

Official Documentation

Every figure in the table above is published by Beckhoff. We reproduce it rather than paraphrase it, so that you can check it against the manufacturer’s own documentation:

• Beckhoff official product page — EL1252 — the source of every specification on this page.
• Beckhoff official documentation for EL1252 — downloadable PDF from Beckhoff’s documentation server.
• Canonical Beckhoff documentation link for EL1252.

Ordering This Part

Tell us the model and, where an order code exists, the complete code — Beckhoff variants differ in ways that matter, as set out above. For discontinued models, a nameplate photograph is the fastest way to confirm exactly what you have.

• Exact model or order code (including any suffix such as -0111 or -ES variants)
• Quantity required
• Whether you need the terminal alone or a complete station with coupler and power supply
• For replacements: a photo of the existing nameplate or the old order code

We confirm availability and condition before quoting. We do not publish stock levels or lead times on this page because they change; ask and we will answer specifically for your requirement.

Frequently Asked Questions

When would I use an EL1252 instead of an EL1008?

When the time of the edge matters. The EL1008 has a 3 ms filter and reports state; the EL1252 has a sub-1 µs input delay and reports a timestamped edge. Flying shears, registration marks, cam triggering and inter-signal timing diagnosis are EL1252 territory.

What accuracy can I actually rely on?

Beckhoff publishes a timestamp resolution of 1 ns and a timestamp accuracy of 10 ns plus input delay between the channels, with input delay below 1 µs. The accuracy figure is the one that matters when comparing two channels.

Does it need Distributed Clocks configured?

Distributed Clocks is supported with an accuracy well below 1 µs. To correlate timestamps system-wide you need DC configured in the EtherCAT master, not just in this terminal.

How many channels does it have?

Two. If you need more timestamped channels, ask us about the rest of the EL125x family — the module exists in several channel counts.

What are the input levels?

Nominal 24 V DC (-15% / +20%). Logic 0 is -3 … +5 V, logic 1 is 11 … 30 V, typical input current 3 mA, following the EN 61131-2 type 3 pattern. Connection is 4-wire.