EL5101

Product information

Product Overview

The EL5101 connects one incremental encoder with differential (RS422) or single-ended (TTL) signals directly to EtherCAT, evaluating input frequencies up to 1 MHz — equivalent to 4 million increments per second with four-fold evaluation.

It is the interface between the physical motion and the controller: a spindle encoder, a measuring wheel, a web encoder, a rotary axis reference.

Why Buyers Specify This Model

Quadrature decoding and microincrements

The terminal performs four-fold evaluation of the A/B quadrature signals with a quadrature decoder, and offers 1/256 bit microincrements for interpolation between encoder increments. The counter is switchable between 16 and 32 bit.

The cut-off frequency of 4 million increments/s corresponds to 1 MHz of input frequency. That covers the great majority of machine encoders; only very high line-count or very fast axes approach the limit.

It powers the encoder, and it checks the cable

The terminal generates the encoder supply itself: 5 V DC at up to 0.5 A, derived from the 24 V power contacts. That removes a separate 5 V supply from the cabinet, and it removes the risk of the encoder losing its reference because a separate supply dropped.

Beckhoff also specifies wire breakage detection. An incremental encoder channel that has lost a conductor does not stop counting — it counts wrongly, which is much harder to diagnose. Detecting the break is what turns a mysterious position error into a clear fault message.

Latch, gate and measurement modes

The latch and gate functions let an external signal freeze or gate the counter, which is how a moving axis is measured against a fixed reference mark. The terminal also measures period duration and frequency, so it can report speed directly rather than requiring the PLC to derive it from position differences.

It supports Distributed Clocks, so the position can be timestamped in step with the rest of the system. The encoder connection is 1 × A, B, C as differential inputs (A, Ā, B, B̄, C, C̄) or single-ended; there is also a 5 V DC status input and a 24 V DC gate/latch input.

Technical Specifications (Official Beckhoff Data)

Parameter	Official value
Technology	incremental encoder interface, differential (RS422), single-ended (TTL), counter, pulse generator
Number of channels	1
Encoder connection	1 x A, B, C: differential inputs (RS422): A, A̅ (inv), B, B̅ (inv), C,C̅ (inv), single-ended connection (TTL): A, B, C, counter, pulse generator: A, B
Additional inputs	status input 5 V DC, gate/latch input 24 V DC
Encoder operating voltage	5 V DC/max. 0.5 A (generated from the 24 V DC power contacts)
Counter	1 x 16/32 bit switchable
Cut-off frequency	4 million increments/s (with 4-fold evaluation), corresponding to 1 MHz
Quadrature decoder	4-fold evaluation
Distributed clocks	yes
Nominal voltage	24 V DC (-15%/+20%)
Resolution	1/256 bit microincrements
Current consumption power contacts	typ. 100 mA + load
Current consumption E-bus	typ. 130 mA
Electrical isolation	500 V (E-bus/field potential)
Special features	wire breakage detection, latch and gate function, period duration and frequency measurement, microincrements, timestamping of edges, filters
Weight	approx. 100 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 EL5101. The ES5101 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)	24 mm x 100 mm x 68 mm

Ordering Information and Variants

Beckhoff’s own ordering information for this product:

Order code	Official description
EL5101	EtherCAT Terminal, 1-channel encoder interface, incremental, 5 V DC (DIFF RS422, TTL), 1 MHz
ES5101	EtherCAT Terminal, 1-channel encoder interface, incremental, 5 V DC (DIFF RS422, TTL), 1 MHz, pluggable wiring level

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 — EL5101 — the source of every specification on this page.
• Beckhoff official documentation for EL5101 — downloadable PDF from Beckhoff’s documentation server.
• Canonical Beckhoff documentation link for EL5101.

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

What encoder types can I connect?

Incremental encoders with differential (RS422) or single-ended (TTL) outputs. The terminal also functions as a counter and pulse generator. It is not an interface for absolute encoders — those use the SSI or BiSS terminals.

Does it supply the encoder?

Yes. It generates 5 V DC at up to 0.5 A for the encoder from the 24 V DC power contacts, so no separate encoder supply is needed for encoders within that current budget.

What input frequency can it handle?

Up to 1 MHz, equivalent to 4 million increments per second with four-fold evaluation. The quadrature decoder uses four-fold evaluation and the counter is switchable between 16 and 32 bit.

Can it detect a broken encoder cable?

Yes. Beckhoff specifies wire breakage detection, along with latch and gate functions, period duration and frequency measurement, and microincrements.

What is the difference between EL5101 and ES5101?

Only the wiring level — the ES5101 has a pluggable wiring level. Both are listed in Beckhoff’s ordering information.