EUCHNER Handheld Operating Unit and Electronic Handwheel Field Troubleshooting Guide

EUCHNER Handheld Operating Unit and Electronic Handwheel Field Troubleshooting Guide

In the setting and operation modes of CNC machine tools, robot debugging, injection molding machines, and automated production lines, handheld operating units (handheld boxes) are essential tools for achieving axis selection, axis movement, emergency stop, and enable control. EUCHNER, a German company with over 60 years of experience in industrial switches and safety technology, has made its HBA, HBM, HBL series manual control boxes and HKB, HKC, HKD, HWA, HWB series electronic handwheels standard accessories for mainstream machine tool manufacturers worldwide, such as DMG MORI, Siemens, Fanuc, etc.

The EUCHNER handheld operating unit is renowned for its compact ergonomic design, IP65 protection rating, modular combination design, and the most eye-catching three-level enable switch (ZXE/ZSE series) and wear-resistant magnetic positioning handwheel. However, any high-precision manual operation equipment will face challenges such as cable core wire breakage, enable switch contact oxidation, loss of handwheel pulse, emergency stop button jamming, and even model discontinuation and inability to purchase after long-term use. On site engineers often face several days of downtime due to a lack of detailed fault diagnosis ideas and accurate alternative model information.

This article is based on the official product technical information of EUCHNER, combined with years of on-site maintenance experience. From the perspective of maintenance engineers, it systematically sorts out the working principles, common fault phenomena, diagnostic processes, module replacement methods, and shutdown selection strategies of handheld operating units and electronic handwheels, helping you quickly restore the manual operation function of machine tools.

Chapter 1 Overview of Product Series and Fundamentals of Security Technology

1.1 HBA/HBM/HBL Handheld Operating Unit

EUCHNER offers three sizes of manual control boxes to meet different quantities of control components and installation space requirements:

Typical Configuration Scenarios for Series Size Grades

HBA minimum and lightest (about 0.8kg) handwheel+emergency stop+2 secondary buttons or 1 tertiary enable+membrane button frequent handheld, space limited operation station

HBM is a conventional machine tool that requires a large number of axis selection and magnification switches, including a medium handwheel, emergency stop, three-level enable, selection switch, and illuminated button

HBL is a high-end device with the largest and strongest (about 2.1kg) handwheel, emergency stop, three-level enable, multiple selection switches, key switch, LCD display screen, complex multi axis, and customizable interface

All shell materials are plastic (HBA/HBM gray RAL 7040, HBL blue gray RAL 7031), with a protection level of IP65 (compliant with NEMA 250 Type 12). The connecting cable can be a spiral cable (stretched to 3.5m or 5m) or a straight cable, with a range of cores from 12 to 42. The plug forms are mostly 23 pin, 26 pin, 28 pin, and 35 pin circular connectors.

1.2 Difference between two-stage and three-stage enabling switches

The Enabling Switch is the most critical safety device in handheld operating units. According to Appendix 1 of the Machinery Directive, when personnel are setting, programming, testing, or repairing in hazardous areas, the protective devices of the machine may temporarily fail, but the machine's movement can only be triggered by an independent, two-step action, and the enable switch must be continuously pressed to maintain movement.

EUCHNER offers two types of enable switches:

Secondary button (2-stage): Press one section → normally open contact closes (enables ON). In emergency situations, the operator may release their grip due to nervousness, at which point the enable will be turned off and the machine will stop. But if the operator holds it tighter instead, the secondary button may continue to be pressed and cannot stop the machine.

3-stage enable switch: patented design, three positions: ① release (OFF) → ② enable (ON) → ③ over press (OFF). When the operator instinctively grips the switch due to fear, the switch enters the third position, the safety contact opens, and the machine immediately stops moving. When returning from position ③ to position ①, the enable zone will be skipped and there will be no accidental restart.

The three-level enable switch is represented as ZXE (such as ZXE-104833 with click feedback) or ZSE (for HBL series, including forced open normally closed contacts) in the EUCHNER model. In the symbol description, 1 NC ①+1 NO represents a forced open normally closed contact and a normally open contact.

1.3 Magnetic and mechanical positioning of electronic handwheel

EUCHNER handwheels are divided into two types based on their positioning methods:

Magnetic determination mechanism: 100 positioning points (per turn) are formed by a magnetic field. No physical contact, theoretically no wear and maintenance, stable positioning torque and no noise. Representative models: HKB, HKC, HKD. Among them, HKB is suitable for flat panel panels and lightweight handheld boxes, HKC is for installation on a tablet console, and HKD has a larger installation depth (≥ 55mm) but is more sturdy, commonly used for HBL handheld boxes.

Mechanical determination mechanism: using a toothed rotor and roller spring structure, with 100 positioning points per turn. Lightweight structure and shallow installation depth. Representative models: HWA (center fixed), HWB (three-point fixed). The packaging is usually in units of 10 or 5 pieces (model suffix/V10,/V05).

Both methods have a pulse count of 100 or 25 per cycle (two channels output orthogonally and can be multiplied). The output circuit can choose RS422 differential signal (A,/A, B,/B, suitable for Siemens system) or push-pull output (A, B, suitable for Fanuc system).

Chapter 2 Common Fault Phenomena and Systematic Diagnosis

2.1 Handheld operating unit: The whole machine has no response or some functions are missing

Phenomenon: After inserting the connector, the device cannot recognize the handheld box; Emergency stop is invalid; Enable switch has no response; The screen coordinates do not change when the handwheel rotates.

Cause investigation:

Cable problem (highest probability ≥ 70%): Spiral and direct cables are frequently bent, and the core wire breaks at the solder joint inside the plug or inside the cable. Common breakpoints are located within 150mm of the entrance at both ends of the spiral or at the plug welding point.

Oxidation or damage of plug pins: 23/26/28/35 pin circular connectors have poor contact in humid or corrosive environments.

Enable switch contact failure: After tens of thousands of presses, the contact resistance increases (normally<0.1 Ω), causing the safety circuit to fail to close.

Emergency stop button not reset: After the emergency stop button is pressed, it does not rotate to reset, and the internal normally closed contacts are still disconnected.

Diagnostic steps:

Measure the pins corresponding to key signals on the connector using a multimeter in the resistance range: emergency stop two pairs of normally closed contacts (should be<0.5 Ω), handwheel power supply 5V and 0V (no short circuit). Measure the resistance of the wires inside the spiral. If any wire is disconnected, it is considered a broken wire.

Swap and test the handheld box with similar devices that are working normally to quickly isolate faults.

If the enable switch is pressed to the second position and no 24V signal (or 0V change) is measured on the corresponding pin, then disassemble the housing (professional tools are required) to check the switch contacts.

2.2 Unstable Handwheel Pulse Output or Incorrect Counting Direction

Phenomenon: When the handwheel rotates, the machine axis moves discontinuously, bounces, or moves in the opposite direction; The magnification selection switch gear is invalid.

Reason:

The magnetic steel of the magnetic positioning handwheel falls off (rare, but will fail after strong impact).

The handwheel output circuit is damaged (RS422 driver or push-pull output chip burned out).

Phase error or reversed wiring of A/B phase signals (confusion between A and/B, B and/A).

The input interface of the controller is not configured for differential reception or the filtering parameters do not match.

diagnosis:

Measure the output of the handwheel using an oscilloscope or multimeter in frequency range: Rotate the handwheel to generate a square wave with a phase difference of 90 ° between phases A and B. The amplitude should be 5V (RS422) or close to the power supply voltage (push-pull). If there is no signal, it indicates that the electronic components inside the handwheel are damaged.

Check encoder interface matching: Siemens CNC systems typically require RS422 differential signals (A,/A, B,/B), while Fanuc systems mostly accept push-pull signals (A, B). Mixing can lead to directional errors or loss of pulses.

Replace the handwheel unit or handwheel module of the same model (HKB/HKD can be replaced separately) for testing.

2.3 The system does not stop after pressing the emergency stop button

Phenomenon: Even after pressing the emergency stop red button, the machine tool can still move.

Severity: ★★★★★ (Safety function failure, must be stopped immediately)

Reason:

The emergency stop contact is not correctly connected to the safety circuit (normally open/normally closed reversed).

Contact sintering after long-term use (high current inductive load).

The emergency stop button does not use a "forced disconnection" structure (EUCHNER emergency stop complies with EN ISO 13850, with two pairs of normally closed contacts for positive drive inside, which theoretically will not fail). But if the external relay contacts are stuck, the power supply can still be maintained after the emergency stop is cut off.

Diagnosis and Solution:

Remove the emergency stop button module and measure the terminals with a multimeter: when released, it should be 0 Ω (normally closed), and when pressed, it should be infinite. If there is still continuity after pressing, the emergency stop module needs to be replaced (such as 096298 long, 106435 short, or 073985).

Confirm that the emergency stop signal is set as a normally closed input in the controller. If the wrong configuration is set to normally open, emergency stop cannot be detected even when disconnected.

Check if the enable circuit of the contactor or servo drive is connected in series with the emergency stop.

2.4 Selection switch (Gray code) and multiplication switch output are confused

Phenomenon: The axis selection switch is in the "X" position but moves the "Y" axis; The actual feed rate is incorrect when the magnification switch is in the "100%" position.

Reason:

Poor internal contact of the switch or detachment of solder joints on the printed board. The Gray code selection switch of EUCHNER (such as 097029~097034) adopts 22.5 ° positioning and outputs 4-bit binary encoding (DCBA). The coding table corresponding to different gears has been provided in the product drawings.

Wiring error: Output lines A, B, C, D are connected incorrectly to the input point of the controller.

The corresponding decoding table is not configured in the controller.

diagnosis:

Turn the selection switch to each gear, measure the common terminal voltage of A, B, C, and D with a multimeter, record the encoded value, and compare it with the drawing. If a gear encoding is incorrect or unstable, the internal contact of the switch is poor and the entire switch module needs to be replaced (knobs and switch bodies can be ordered separately).

Chapter 3: On site Replacement and Spare Parts Replacement Strategies

3.1 Replacement of cables and connectors

EUCHNER provides original cable components: 12 core, 23 core, 35 core spiral or direct connection cables with pre installed plugs. Replacement steps:

Turn off the power and remove the back cover of the handheld box (be careful with wiring).

Record the original cable core color and pin number (or take a photo).

For soldered plugs (such as 23 pins), use an electric soldering iron to remove the solder and disconnect the wires. The new cable should be welded according to the original definition, and attention should be paid to the single end grounding of the shielding layer (connected to the shell).

After reassembling, use a multimeter to test the key signals for on-off.

Confirm that the pins are not short circuited before power on testing.

If the original cable model has been discontinued, you can choose a universal spiral cable with the same number of cores and similar outer diameters, and purchase matching connectors separately (EUCHNER provides 23, 28, and 35 pin flange sockets and short-circuit plugs, with models such as 074384). When making homemade cables, it is necessary to ensure the coverage of the shielding layer and the bending resistance performance.

3.2 Replacement of Enable Switch

When the third level enable switch ZXE or ZSE fails (contactless switching or disappearance of clicking sound), you can order:

ZXE-091336:2 normally open contact, no clicking sound.

ZXE-104833:2 normally open contact with operation click sound (more suitable for tactile feedback).

ZSE2-2 C1692 (2NO+1NC) or ZSE2-4 C1943 (2NO+2NC) is used for HBL shell.

Attention: Replacing the enable switch requires disassembling and assembling the entire housing and internal printed circuit board. After soldering the 6 pins (or 4) of the old switch, clean the solder pads, insert the new switch, and solder it. After installation, a functional test must be conducted: press to the second position to confirm that the two normally open contacts are closed; Press excessively to the third position and confirm that the contact is disconnected; After release, the contact point should be disconnected when returning to the first position.

3.3 Replacement of Handwheel

Recommended replacement models for discontinued old models, attention points

HKB100S7A05 (RS422, 5V) HKB100S7A05K (with key function) or HKB100S7A12 (10-30V power supply) Pay attention to the power supply voltage and output type

HKD100S100G05 (push-pull 5V) HKD100S100G24 (push-pull 10-30V) G24 output signal amplitude is Ue-3V, need to confirm controller input level

HWA/T series (10 packages) HWA100T100A05/V10 can be used for Siemens systems

HWB series 5-pack HWB100T100G05/V05 suitable for Fanuc

Key steps:

Mark the positioning direction of the handwheel and panel before disassembly (usually the handwheel has a positioning pin hole).

The connecting cable between the handwheel and the control box (usually a 6-core flat cable) needs to be carefully plugged and locked with a buckle.

After replacing the handwheel, a direction test is required: clockwise rotation should generate a pulse of A phase leading B phase by 90 ° (according to the controller definition). If the direction is opposite, there are two solutions: ① Swap A with B (or A with/B); ② Reverse the direction of the handwheel in the numerical control parameters (such as Siemens setting MD32100).

The magnetic positioning handwheel does not require lubrication. If the mechanical positioning handwheel (HWA/HWB) feels rough, the positioning groove can be cleaned and lightly coated with low-temperature grease.

3.4 Emergency Stop and Selection Switch Replacement

Emergency stop button: 096298 for long models (for HBA/HBM shells without enabling windows); Short version (HBA HBE with enable window) with 106435; HBL uses 073985.

Blind hole cover plate (for sealing when emergency stop is not installed): 083653 (22mm aperture).

Selection switch: Different gear switch units (such as 097029 five gear gray code, 097033 twelve gear gray code) and matching knobs (097141 black) can be ordered separately. When replacing, pay attention to the "disconnect before closing" or "short-circuit" characteristics of the switch, which must be consistent with the original design. C

Chapter 4: Key Points for Installation, Wiring, and Debugging

4.1 Handheld Box Holder Matching

EUCHNER offers dedicated hangers: HBA hangers are available in gray (072828) and black (100221), as well as gray (072935) and black (109979) with large handwheel slots. HBM hanger (112335), HBL hanger (084397). The hanger is fixed to the machine control panel or wall by screws. Choosing the wrong hanger can result in the handwheel not being able to rotate freely in the hanger or being difficult to retrieve and place.

4.2 Correspondence between plugs and sockets

Handheld box connector pin number device side flange socket (with short-circuit plug) matched with cable plug

12-pin 086749 086748

23-pin 074384 074393

28-pin 074385 074394

35-pin 074386 074395

When the device is not in use, the short-circuit plug needs to be inserted into the flange socket for sealing (such as the 103042 set containing a 26 pin flange and short-circuit plug).

4.3 Wiring Checklist

Emergency stop circuit: normally closed dual channel, independently forming a safety circuit without going through PLC logic.

Enable switch: If using secondary buttons (S2, S3), the normally open contacts can be connected to the "enable input" of the safety module or directly connected in series in the servo enable circuit (depending on the safety level design).

Handwheel wiring: RS422 differential signals (A,/A, B,/B) should be twisted pair shielded, with the shielding layer grounded at one end. Power supply 5V ± 5% or 10-30V.

Axis selection/magnification switch: Connect to the PLC digital input module, and it is recommended to use 0V for the common terminal.

Membrane button or illuminated button: LED requires an external current limiting resistor (approximately 1k Ω at 24V), pay attention to polarity.

4.4 Debugging steps

After connecting the handheld box, check the status of the emergency stop input signal on the system diagnostic interface (normally it should be 1, pressing the emergency stop button should be 0).

Enable switch: Press to the second position and check if the corresponding PLC input point has changed to 1.

Rotate the handwheel and observe whether the position counter increases or decreases smoothly, and whether there are any missing steps (the position should change linearly when rapidly rotating continuously).

Test the gear positions of the axis selection switch and the magnification switch to confirm that the coding is correct.

Chapter 5 Maintenance Suggestions and Life Extension Measures

Periodic maintenance project method

Check the cable entrance daily for wear and tear, and visually inspect for broken spiral wires. If the outer skin cracks, repair it promptly with a heat shrink tubing

Test the emergency stop and enable switch functions weekly and observe the machine's response

Use electronic contact cleaner spray to clean connector pins every month

Measure the output signal quality of the handwheel quarterly (using an oscilloscope), record the pulse amplitude and phase, and compare with the initial results

Check the internal welding points and wiring every year, open the shell, and re weld the virtual welding points

Replace frequently operated membrane buttons as needed (HBA provides aluminum panel for front panel without/with handwheel) Order 084395/084396 (without handwheel), 083635/083636 (with handwheel)

Special reminder: The design of the EUCHNER handheld operating unit allows for resistance to oil stains and coolant at IP65 rating, but should not be immersed. Cables should be inspected regularly, and it is recommended to replace the spiral wire every 3-5 years (especially for production lines that operate 24 hours a day).

Chapter 6 Rapid Replacement Process for Discontinued Models

When the handheld box cannot be repaired as a whole or the prototype number is no longer in production (such as when the old HBE series has been replaced by HBA/HBL), the following process can be taken:

Record the original interface pin definitions: including pin assignments for all buttons, handwheels, and emergency stops.

Choose existing models with the same function: for example, the original handheld box has "axis selection switch (6 positions) x 1+magnification switch (5 positions) x 1+emergency stop+handwheel", and HBA-100186 (selection switch 5 positions+6 positions+handwheel+2 secondary buttons+emergency stop) can be selected. If there is no identical configuration, the HBA/HBM/HBL kit can be used for self-assembly (order numbers for HBA housing kit on page 29, HBM kit on page 37, HBL kit on page 41), and individual switches, handwheels, cables, and flange sockets can be selected for self welding and assembly.

Copy wiring: Cut off the original cable plug and re crimp or solder according to the pin definition of the novice holder box (note that the polarity of the emergency stop and enable contacts must match the original safety circuit).

Testing: After replacement, a full functional test is required, especially for the reliable disconnection of safety functions (emergency stop and enable).

EUCHNER provides complete customization services (see the Request Form in the appendix), which can be filled in with customer requirements and produced in small batches by the original factory with a delivery time of usually 6-8 weeks.