Category: Sensor Selection

M18 is the size most Indian plants actually run on. It is large enough to give useful sensing distance, small enough to fit where it is needed, and the bracket for it already exists on most machines. If you are designing a sensor in or replacing one, these are the numbers that matter.

The thread pitch catches people out

Proximity sensors in M18 use a fine thread, M18 x 1, not the coarse M18 x 1.5 you would use for a general fastener. The fine pitch gives finer adjustment of the sensing gap, which is the whole point of a threaded barrel with locknuts either side.

The practical consequence: an M18 x 1.5 nut will not run on an M18 x 1 sensor, and a bracket tapped M18 x 1.5 will not take one. If you are drilling a new bracket, make it a clearance hole and clamp with the locknuts rather than tapping it. That also lets you adjust the gap, which a tapped hole does not.

When ordering replacement locknuts, specify M18 x 1. Ordinary hardware shops will hand you coarse by default.

Sensing range, and the number you should actually design to

Our D30C range offers M18 in two sensing distances, 5 mm and 8 mm. The 5 mm version is shielded and can be mounted flush in metal. The 8 mm version senses further and needs a clear zone around the face.

Three numbers get quoted for sensing distance and they are not the same:

• Rated sensing distance is the nominal figure, measured against a standard mild steel target under standard conditions.
• Effective sensing distance allows for manufacturing tolerance.
• Assured operating distance allows for tolerance, temperature and supply voltage variation together. This is the number you design to.

As a working rule, set the mounting gap at around 70 to 80 percent of the rated distance. An M18 with 5 mm rated should see the target at 3.5 to 4 mm, not at 4.8 mm. A sensor set at the edge of its range works on the bench and becomes intermittent in the hottest month of the year.

Then correct for the target. Stainless steel, aluminium, brass and copper are all detected at less than the rated distance. Our reduction factor table has the arithmetic, and it is the single most common reason an M18 that should work does not.

Mounting clearances

These matter as much as the sensing distance, and they differ between shielded and unshielded.

A shielded sensor has a metal sleeve concentrating the field forward. It can be embedded flush in a steel bracket with the face level with the surrounding metal.

An unshielded sensor lets the field spread sideways. Mount it flush in steel and it will detect the bracket and stay on permanently, which gets diagnosed as a faulty sensor roughly half the time. It needs a clear zone around the face and must stand proud of the mounting surface.

Two more clearances apply to both: keep a gap between adjacent sensors so their fields do not interact and cause chattering, and keep metal out of the area facing the sensor other than the target itself. Our note on shielded versus unshielded mounting gives the spacing rules.

Tightening

A proximity sensor barrel is a thin-walled tube with electronics potted inside it. It is not a bolt. Over-tightening the locknuts crushes the barrel and damages the sensor, and it is a surprisingly common cause of failures that look electrical.

Use a locknut on each side of the bracket, tighten by hand plus a short turn with a spanner, and do not use an impact driver. If the sensor needs to resist vibration, use a thread locking compound rather than more torque.

Cable, or connector

M18 sensors are supplied either with a fixed cable or with an M12 connector on a short pigtail. The connector version is worth specifying where the sensor is removed regularly for changeovers, because a cable pulled through a machine frame every week eventually fails at the gland. Where the sensor is fitted once and left, fixed cable in the exact length you need removes a junction box.

We can supply either, with the cable length specified rather than standard. On a machine build that is usually worth asking about.

Ordering an M18

The code is readable once you know the pattern. D30C-1805-PM-3S is an M18 body, 5 mm sensing, PNP, normally open, three-wire with short-circuit protection. Swap the digits for 1808 and you have the 8 mm version. Our part number guide decodes the whole range.

If you need a dimensional drawing for a design, ask and we will send it. Tell us the target material, the gap you have to work with, whether the sensor can stand proud of the bracket, and the output your input card expects, and we will confirm the variant and the mounting arrangement before you commit the design.

The enquiry usually arrives in the same form: we need an inductive sensor with more range than the one we have. It is a reasonable request and there are four legitimate ways to satisfy it — plus a point at which the right answer is a different technology altogether.

Why inductive range is limited at all

An inductive sensor works by generating a high-frequency field at the sensing face and detecting the energy lost when a conductive target enters it. Field strength falls off sharply with distance, so the usable range is set primarily by coil diameter. A bigger coil produces a field that reaches further.

Everything below follows from that.

1. Use a larger body

The most direct route. Across the D30C range, sensing distance rises with body size:

• M8 — shortest
• M12 — 4 mm
• M18 — 5 mm and 8 mm
• M30 — 10 mm and 15 mm
• M36 — 20 mm
• M50 — 30 mm

Thirty millimetres from an M50 is the practical ceiling for standard inductive sensing. If the geometry allows a larger body, this is the cheapest and most reliable answer, and it comes with a bonus: the extra standoff tolerates dust, scale and mechanical slop far better than a short-range sensor mounted close.

2. Use an unshielded sensor

A shielded sensor has a metal sleeve around the coil that concentrates the field forward, which allows flush mounting in metal at the cost of range. An unshielded sensor lets the field spread and reaches noticeably further in the same body size.

The price is mounting freedom. An unshielded sensor needs a clear zone around the sensing face — mount it flush in a steel bracket and it detects the bracket, permanently. That failure presents as a sensor stuck on, and gets misdiagnosed as a faulty sensor regularly.

Our note on shielded versus unshielded sensors gives the clearance requirements.

3. Fix the target

This is the option people skip, and it is frequently the best one because it costs nothing.

Rated sensing distance is quoted against a standard mild steel target of a defined size. Two things reduce it in practice:

Material. Stainless steel, aluminium, brass and copper are all detected at less than the rated distance, each by a different factor. If you are sensing aluminium at what you believed was 80 percent of rated range, you may actually be at the limit. Our note on reduction factors for different metals has the numbers.

Size. A target smaller than the standard is detected at reduced distance. Enlarging it — adding a mild steel flag or tab to an aluminium component — often recovers all the range you were missing, for the price of a bracket.

Before specifying a bigger sensor, check whether a bigger target solves it. It usually does, and it is almost always cheaper.

4. Move the sensor

Obvious, and worth stating. The distance that matters is between the sensing face and the target at its closest approach. A mounting position 10 mm closer is worth more than any specification change, and often available once someone looks at the bracket rather than the catalogue.

When to stop and change technology

Past about 30 mm, pushing inductive sensing is the wrong exercise. The alternatives:

Photoelectric — ranges from 100 mm to 20 metres depending on mode, and works on non-metallic targets. Needs reasonable cleanliness, and mode choice matters; see the D31C range.

Capacitive — for non-metallic targets at short range, and the only practical answer for sensing through a non-metallic wall. See capacitive sensing for plastic and powder.

Magnetic — senses a magnet at greater distance than an inductive sensor senses steel, and works through non-ferrous walls. Requires a magnet on the target, which is a constraint but sometimes an easy one.

Position transducer — if what you actually want is not presence at a distance but continuous position, no proximity switch will give it. The Novotechnik range covers that properly.

Sensitivity is not the whole story

One caution about chasing maximum sensitivity. The rated sensing distance is a nominal figure; the assured operating distance you should design to is shorter, because of manufacturing tolerance, temperature drift and supply variation.

A sensor set up at the very edge of its range works on the bench and becomes intermittent in service — typically in the hottest month, which makes it look like an environmental fault rather than a specification one. Design to the assured distance and leave margin.

What to send us

The distance you need, the target material and size, whether the sensor can be mounted non-flush, the available body size, and the environment. If you are currently marginal rather than starting fresh, tell us what you have and what it is doing — an intermittent sensor and a sensor that never triggers are different problems with different answers.

Most position sensors are sold as complete units: housing, bearing, shaft, seals and electronics, ready to bolt on. For an OEM building a few hundred machines a year, that packaging is sometimes the wrong product. You already have a housing, you already have a bearing, and you are paying for someone else version of both.

A sensor kit is the alternative — the measuring element and wiper supplied as components, for mounting into your own mechanics. Accent supplies these from both Contelec and Novotechnik as authorised distributor for India and SAARC.

What a sensor kit actually is

A potentiometric sensor kit is an absolute resistance element and a matched wiper assembly, designed to be installed into a closed device that the machine builder provides. Position is read as a voltage ratio across the element, exactly as in a packaged transducer — the difference is who supplies the mechanics.

The range we supply includes:

• PTN and PTX — absolute potentiometric resistance elements and wipers, for mounting in a closed device
• PRS — resistance element and wiper combination with high accuracy
• PTP — potentiometric position transducer in a cost-optimised compact design, where you want a packaged unit but a small and inexpensive one

What you gain

Cost. You are not buying a housing, a bearing and a shaft seal you already have. On volume production this is the main driver.

Space. A kit integrated into existing mechanics is substantially more compact than a packaged transducer bolted onto them. Where the machine is already tight, this is sometimes the only way position measurement fits at all.

No coupling. A packaged rotary transducer needs coupling to the shaft, and that coupling introduces backlash, misalignment and a wear point. An integrated element rides on the shaft you already have.

Ingress protection by design. If the element sits inside a housing you have already sealed, the sensor inherits that sealing rather than needing its own.

What you take responsibility for

Being direct about this, because it decides whether a kit is appropriate.

Bearing quality and alignment. In a packaged transducer the manufacturer controls the relationship between shaft and element. With a kit, you do. Radial play translates directly into wiper tracking error, and a worn bearing produces a noisy output that looks like a failed sensor.

Wiper pressure and contact geometry. Specified by the manufacturer and set by your assembly. Too light and the contact becomes intermittent; too heavy and the element wears prematurely.

Contamination control. The element is exposed to whatever is inside your housing. Swarf, condensation and grease migration all cause problems that a sealed packaged unit would have excluded.

Assembly consistency. The measurement is only as repeatable as your build process. This needs a documented assembly procedure and an end-of-line check.

When a kit is the right decision

Yes — volume production, an existing housing with a well-supported shaft, space constrained, and an assembly process capable of holding the tolerances.

No — low volume or one-offs, where the engineering effort is not repaid. Retrofits onto existing machines. Harsh or contaminated environments where a sealed packaged unit is safer. Anywhere the assembly cannot reliably hold wiper geometry.

Packaged rotary alternatives

If a kit is not right, the packaged potentiometric rotary range covers most requirements:

• IP-6000 — absolute high-precision potentiometric rotary sensor, robust and sealed
• IPX-7900 — high-precision potentiometric rotary for harsh conditions, available to IP69
• GP — high-precision potentiometric rotary with reduction gear, for measuring across more than one input revolution
• AW-360 — high-precision rotary in a robust design with gap-free output voltage across the full turn, useful where the measurement must not have a dead band at the wrap point
• SP-2800 — compact and robust absolute potentiometric rotary, straightforward to install and adjust
• F200 — absolute inductive transducer with centering collar and integrated sealed hybrid electronics, where a non-contacting element is preferred

The gap-free question

Worth understanding before specifying any single-turn rotary sensor. Most potentiometric elements have a small dead band at the point where the track ends and begins again — a few degrees where the output is undefined. If your measurement never crosses that point, it does not matter. If the shaft rotates continuously through it, the output jumps.

Where that matters, specify a gap-free type such as the AW-360, or a touchless design. It is a cheap thing to get right at specification and an expensive thing to discover at commissioning.

Getting a recommendation

For a kit, send us the shaft diameter, the available space, the measuring angle, the bearing arrangement, and your annual volume. For a packaged unit, the mounting arrangement, measuring angle, required accuracy, output and environment. If you have a drawing of the housing the sensor has to live in, that answers most of it at once.

A single-turn rotary sensor measures position within one revolution. Turn the shaft past 360 degrees and it starts again at zero. For a valve actuator or a throttle that is exactly right. For a crane hoist, a leadscrew, a winch or a steering column, it is useless — you need to know which revolution you are on.

That is what a multi-turn sensor provides, and the interesting question is how it remembers.

True-Power-On: why it matters

Traditional multi-turn designs count revolutions. That works while powered. Remove the power and the count has to be preserved somehow, which historically meant one of two compromises:

A battery, which keeps the counter alive. Batteries fail, and when one does the position is lost — usually discovered at the worst moment, and requiring a re-reference before the machine can move safely.

A mechanical gear train, which stores the turn count physically. No battery, but gears add size, backlash and a wear mechanism.

Novotechnik NOVOTURN technology takes a third route. The sensor determines absolute position across the full multi-turn range at power-up, without a battery and without a gear train. If the shaft is moved while the power is off — by hand, by gravity, by a load slipping — the sensor reports the true new position when it powers up, not the position it remembers.

For anything where an unexpected movement during a shutdown is possible, this is the difference between resuming safely and needing a manual re-reference.

The four series

MB1-3600 — absolute non-contacting multi-turn with True-Power-On NOVOTURN, in a 36.5 mm all-metal housing. The all-metal construction is the reason this one gets specified for rough duty. Available with CANopen and IO-Link.

MC1-2800 — NOVOTURN multi-turn with smart sensor functions, in a more compact 28 mm format. Also available with CANopen and IO-Link. The choice where space is constrained.

MZ1-2200 — NOVOTURN multi-turn with smart sensor functions in the smallest format of the three, 22 mm. CANopen available. For tight installations where an MC1 will not fit.

RMB-3600 — absolute non-contacting NOVOHALL multi-turn in a 36.5 mm all-metal housing, with analogue and digital interfaces and several versions available. NOVOHALL rather than NOVOTURN, so confirm the power-off behaviour against your requirement if the shaft can move during shutdown.

Smart sensor functions

The MC1 and MZ1 carry what Novotechnik describes as smart sensor functions. In practice this means parameters that would traditionally be fixed at manufacture — measuring range, zero point, direction of rotation, output scaling — can be configured rather than ordered.

Two consequences worth planning around. Commissioning gets faster, because the sensor is adjusted to the machine rather than the machine to the sensor. And spares holding gets simpler, because one configurable part can cover several positions that would otherwise need distinct part numbers.

If you hold spares across a fleet, ask about this specifically — it often reduces the number of variants you need to stock.

Choosing between them

1. Start with the housing size. 36.5 mm, 28 mm or 22 mm. Mechanical space usually decides this before anything else does.
2. Then the interface. CANopen across all three NOVOTURN series, IO-Link on MB1 and MC1, analogue and digital on RMB.
3. Then robustness. The all-metal 36.5 mm housings of MB1 and RMB suit exposed and mobile applications.
4. Then configurability. If you want smart sensor functions, MC1 or MZ1.

Where multi-turn is the right answer

• Crane and hoist position — drum rotation over many turns, where the load position must be known immediately at power-up
• Leadscrew and spindle position — linear motion driven through many revolutions
• Winch and cable drums
• Steering angle on mobile machinery, where lock to lock exceeds one turn
• Multi-turn valve actuators — gate and globe valves that take many turns to stroke
• Roll gap and screwdown adjustment in rolling mills

The common thread is that the mechanism travels through more than one revolution and the machine has to know where it is without a homing move.

When a single-turn sensor is enough

If total travel stays within one revolution, use a single-turn sensor — it is simpler and cheaper. The single-turn range covers that, including the RSC-2800 and RFC-4800.

Where a gearbox reduces a multi-turn mechanism to under one revolution at the measuring point, a single-turn sensor also works — but check the backlash, because it appears directly in your position reading.

Specifying

Send us the total number of revolutions, the resolution required, whether the shaft can move while the power is off, the interface your controller expects, the mechanical arrangement and available space, and the protection rating needed. Accent is the sole authorised Novotechnik distributor for India and SAARC.

The Novotechnik linear position transducer range covers four distinct measurement technologies across more than a dozen mechanical formats. Approached as a catalogue it is bewildering. Approached as three questions it resolves quickly.

The questions are: how is it mounted, how long does it have to last, and does anything need to be inside a cylinder.

The four technologies

Potentiometric — a precision conductive plastic track with a wiper. Simple, absolute, direct DC output, no conditioning electronics, lowest installed cost. The wiper contacts the track, so there is a wear mechanism, though Novotechnik designs use a decoupled wiper tap and pendular fixed slide bearing specifically to give stick-slip-free movement and long life.

NOVOSTRICTIVE (magnetostrictive) — non-contacting. A magnet moves along a waveguide and position is derived from the timing of a returned pulse. No wear in the measuring path, long strokes available, and it can be built as a rod for installation inside a hydraulic cylinder.

NOVOPAD (inductive) — non-contacting inductive measurement in a compact profile. A wear-free alternative in a smaller package than magnetostrictive.

Integrated signal processing types — the TE1 family, which includes signal processing in the transducer and can be replaced without recalibration. That last property is worth noting for maintained plant: swapping the unit does not mean a commissioning exercise.

Question one: how does it mount

This narrows the field faster than anything else.

Rod style, actuated by a moving machine element

• TEX rod type — potentiometric, pendular fixed slide bearing, decoupled wiper, long life
• TX2 — potentiometric with a double-supported actuating rod, high adjustment speed. Available with pivot head mounting or mounting clamp.
• LWH and LWG — potentiometric, the general-purpose workhorses of the range
• LWX-003 and LWX-004 — the LWX-004 with a shaft-protected design for dirtier positions

Side actuated

• TLH — potentiometric, side actuated, IP40 to IP54, rated from below minus 30 to above plus 100 degrees Celsius

Spring return, where the machine pushes but does not pull

• TR and TRS with return spring, TEX with return spring, TE1 with return spring, LS1 with return spring

A return spring matters more than it sounds. If the actuating element only pushes the rod and relies on it following back, the spring is doing the measurement on the return stroke — and if it is absent or too weak for the speed, the reading lags.

Profile designs

• TP1 — NOVOSTRICTIVE magnetostrictive in a robust profile, non-contacting
• LS1 — NOVOPAD inductive, compact profile, double-sided supported actuating rod

Inside a hydraulic cylinder

• TH1 — NOVOSTRICTIVE rod style, designed for integration into cylinders

Sensor kits for integration into your own housing

• PTX — potentiometric sensor kit, for OEMs building the transducer into their own mechanics

Question two: how many cycles

This decides contacting against non-contacting.

For machine positioning, valve feedback, press setup and general industrial measurement at moderate cycle rates, potentiometric is entirely adequate and considerably cheaper installed. The objection people raise — that the wiper wears — is usually based on experience with wirewound potentiometers rather than conductive plastic elements with decoupled wipers.

For continuous high-cycle duty, for washdown environments, or where a failure is expensive enough that the wear mechanism is unacceptable in principle, specify NOVOSTRICTIVE or NOVOPAD. The cost difference buys the removal of the only wear path.

Question three: cylinder integration

If the measurement has to happen inside a hydraulic cylinder, the answer is TH1 and the other questions become secondary. A rod-style magnetostrictive transducer installed in a gun-drilled cylinder rod gives you position with nothing exposed to the outside world at all — no rod to be damaged, no seal to fail, no alignment to lose.

This is the right answer for mobile machinery, presses and any cylinder in a position where an external transducer would be destroyed.

Interfaces

Most of the range offers ratiometric or analogue output as standard. TH1, TP1 and TM1 also offer CANopen and IO-Link, which is worth knowing if the machine architecture is bus-based — see CANopen position sensors.

A quick way through

1. Inside a cylinder? TH1.
2. OEM integration into your own housing? PTX.
3. High cycles, wet, or wear unacceptable? TP1 or LS1.
4. Needs to be replaceable without recalibration? TE1.
5. Everything else — LWH, TEX or TX2 depending on mounting, with a return spring variant if the actuator only pushes.

What to send us

Stroke length, mounting arrangement, whether the actuator pushes only or both ways, expected cycles per day, required accuracy as a number, output needed, protection rating, and temperature range. A sketch of the mechanical arrangement is worth more than any of them individually. Our note on selecting a linear position transducer covers the mechanical decisions in more depth.

A lot of linear position enquiries in India arrive asking for an LVDT. Often the application genuinely needs one. Just as often the buyer is asking for an LVDT because that is the technology they encountered first, and a potentiometric or Hall-effect transducer would do the job for less money, with shorter lead times and easier support.

This is a comparison of the three technologies from a purchasing point of view rather than a physics one, so that the enquiry you send matches the problem you have.

LVDT: what it is genuinely good at

A linear variable differential transformer measures displacement through electromagnetic coupling between a primary coil and two secondary coils, with a movable core. Because the core does not touch the coils, there is no wear in the measuring path.

Its real strengths are narrow and worth respecting:

• Very high resolution over short strokes. Sub-micron measurement is achievable. For metrology, materials testing and precision gauging, nothing else is as appropriate.
• Effectively infinite mechanical life in the measuring path.
• Excellent repeatability in a controlled environment.

The costs are equally specific. An LVDT needs AC excitation and signal conditioning electronics, so the installed cost is well above the sensor price. Strokes are typically short. And the whole assembly is more expensive than the alternatives by a margin that is difficult to justify unless you are actually using the resolution.

Potentiometric: the workhorse

A potentiometric transducer is a precision resistive track with a wiper. Apply a voltage across the track and the wiper delivers a voltage proportional to position. It is the simplest possible arrangement and it remains the correct answer for a large share of industrial stroke measurement.

• Direct DC output with no conditioning electronics required
• Absolute by nature — position is known at power-up with no homing
• Long strokes available, well past what LVDTs practically cover
• Substantially lower installed cost

The trade-off is the wiper. It is a contacting device, so in very high-cycle applications the track eventually wears. In practice, for machine positioning, hydraulic cylinder feedback, valve position and press ram measurement, this is rarely the limiting factor — and Novotechnik conductive plastic elements are considerably more durable than the wirewound potentiometers the objection usually has in mind.

The Novotechnik potentiometric range we supply covers a wide span of formats: TLH side-actuated, LWH, LWG and LWX, the TR and TRS spring-return units, TEX in rod and pivot-head mountings, TE1, TX2, and the PTX sensor kit for integration into a customer housing.

Hall-effect and touchless: the modern middle ground

Magnetic touchless transducers give you the wear-free measuring path of an LVDT without the excitation and conditioning overhead. There is no contact, the output can be a straightforward analogue signal or a digital bus, and protection ratings can be very high because nothing has to penetrate the housing.

For high-cycle industrial applications that do not need sub-micron resolution, this is frequently the correct modern answer, and it is where a lot of applications that would once have used an LVDT now sit.

Choosing between them

Specify an LVDT when you need sub-micron resolution over a short stroke, in metrology, materials testing or precision gauging — and when you have budgeted for the signal conditioning.

Specify potentiometric for general machine positioning, cylinder feedback, valve position and press applications, where you need a reliable absolute reading, a simple DC output and a sensible price. This covers most industrial enquiries.

Specify touchless when cycle counts are high, the environment is hostile, washdown is involved, or you want the position on a fieldbus.

On sourcing LVDTs in India specifically

Worth being direct: we do not manufacture LVDTs, and we would rather say so than sell you something adjacent and call it equivalent. What we do supply is the full Novotechnik linear position transducer range as sole authorised distributor for India and SAARC, covering potentiometric and touchless technologies across a wide range of strokes and mountings.

If your application genuinely requires an LVDT, tell us and we will say so. If it does not — and in our experience most do not — we can usually offer a transducer that is available faster, costs less installed, and needs no signal conditioning.

What to send us

• Stroke length required, and the mechanical space available
• Resolution and accuracy genuinely needed, as a number rather than as high
• Expected cycles per day and the intended service life
• Output required and the controller it feeds
• Environment: temperature, protection rating, washdown, vibration
• Mounting arrangement, and whether a return spring is needed

Our guide to selecting a linear position transducer covers the mechanical decisions in more detail.

Machine builders standardising on CAN keep arriving at the same question: can we take position measurement onto the bus rather than running it as analogue into an input card? For most of the Novotechnik range the answer is yes, and the reasons to do it are more practical than they first appear.

What moving position onto CANopen actually saves

An input card and its wiring. Each analogue position signal needs a channel, a screened cable run and a termination. On a machine with six position measurements that is most of a card plus the loom.

The analogue conversion chain. A digital sensor reports position as a number. An analogue one reports a voltage or current that then has to be scaled, and every step in that chain contributes error and drift. Removing it removes a calibration task from commissioning and a drift mechanism from service.

Diagnostics. This is the benefit that justifies the change on its own. An analogue sensor reading mid-scale is indistinguishable from a healthy sensor at mid-position. A bus device reports its own status, so the controller knows the difference between a sensor saying halfway and a sensor that has stopped talking.

Commissioning time. Parameters set over the bus rather than by trimming.

Which series carry CANopen

From the Novotechnik range we distribute in India, CANopen is available on:

Rotary sensors

• RSA-3200 — single-turn
• RFX-6900 — absolute touchless redundant heavy duty
• RSX-7900 — absolute non-contacting redundant heavy duty
• MB1-3600, MC1-2800 and MZ1-2200 — multi-turn

Linear transducers

• TH1
• TP1
• TM1 with plug-in flange and TM1 with screw flange
• TF1

Several of these also support IO-Link — MB1-3600, MC1-2800, TF1, TH1 and TP1 — which is worth knowing if your architecture uses IO-Link masters at the machine level rather than CAN throughout.

What to confirm before ordering

Fieldbus variants are configured to the protocol at manufacture. This is not a setting that can be changed on site, so the following need to be right at order stage.

1. CANopen specifically, not CAN generally. CANopen, J1939 and proprietary CAN implementations all run on the same physical layer and do not interoperate. Confirm which one your controller actually speaks.
2. The device profile. Encoder devices commonly follow CiA 406. Check your master expects that profile.
3. Node ID and baud rate setting method. Whether these are set by hardware switch, by configuration over the bus, or fixed at order.
4. Termination. Whether the sensor includes a terminating resistor or whether you supply it. A bus terminated twice, or not at all, is a classic commissioning fault.
5. Redundancy. RFX-6900 and RSX-7900 offer redundant measurement channels. If the position feeds a safety function, specify this at the start.
6. The EDS file. Ask for it with the quotation, not after delivery.

When analogue is still the right answer

Bus is not automatically better. Analogue remains sensible when you need one position signal rather than several, when the controller has a spare analogue input and no CAN master, when you are replacing a single sensor in an existing machine, or when the maintenance team is set up for analogue troubleshooting and not for bus diagnostics. Converting one sensor to CANopen on a machine that is otherwise entirely analogue adds complexity without collecting the benefit.

Where a mixed approach makes sense, several of these series are available in both analogue and bus variants, so the mechanical design can stay identical while the interface differs.

Ordering

Send us the measurement required — angle or stroke — the controller and CAN master you are using, the profile expected, the mechanical arrangement, the protection rating needed, and whether redundancy is required. Accent is the sole authorised Novotechnik distributor for India and SAARC, so configuration questions go back to the factory rather than being guessed at.