Cymotorix, a China closed loop stepper motor manufacturer and supplier, builds closed loop stepper motors from NEMA 23 (57mm) to NEMA 42 (110mm), each with an encoder mounted on the shaft. The encoder feeds actual rotor position back to the driver, which corrects any position error in real time — so the motor holds its commanded position even when the load changes, with no lost steps. Holding torque runs from 0.3 N·m to 12 N·m across the range. A closed loop stepper motor gives you the wiring simplicity of a stepper with reliability close to a servo, at a lower cost. We supply the motor and its matched driver as a tested set. The pages below break each NEMA size into its own spec sheet.
NEMA 23 to NEMA 42 frames with a built-in encoder, holding torque from 0.3 N·m up to 12 N·m, wound and tested in our own Changzhou plant.
Encoder feedback corrects position error in real time, so the motor never loses a step even when the load changes.
Motor and matched closed loop stepper driver supplied and tested as a set, so commutation and tuning are sorted before it ships.
Standard samples ship in 3–5 days. Custom prototypes in 10–15 working days. Selection questions answered within 24 hours.
We build three main types of stepper motors — 2-phase, 3-phase, and closed loop. The 2-phase hybrid is our highest-volume product, covering NEMA 8 through NEMA 42. If your application needs lower vibration at higher speeds, go with 3-phase. If you need position feedback and anti-lost-step protection, the closed loop series is the right fit.
| Closed Loop | Open Loop (2 Phase) | AC Servo | |
|---|---|---|---|
| FEEDBACK | Encoder on shaft | None | Encoder on shaft |
| LOST STEPS | Corrected in real time | Possible under overload | None |
| STEP ANGLE | 1.8° | 1.8° / 0.9° | Continuous |
| FRAME SIZE | NEMA 23–42 | NEMA 8–42 | 60–180mm |
| BEST FOR | Anti-lost-step, variable load | Low-cost positioning | High speed, high dynamics |
· 1.8° step angle with encoder feedback (1000-line incremental standard)
· Holding torque from 0.3 N·m to 12 N·m across NEMA 23–42
· Real-time position correction, no lost steps under varying load
· CE and RoHS certified, 80°C max temperature rise
· Mechanical: shaft diameter and length, flange, mounting holes, lead exit direction
· Electrical: winding voltage and current, connector type, encoder resolution
· Integration: gearbox or brake mounted and tested with the closed loop unit
· Branding: your logo on the motor body, custom labels and packaging
· 1000-line incremental encoder (standard)
· Higher-resolution incremental on request
· Absolute encoder for position memory without homing
· Rear-shaft mounting, sealed against dust
· Matched closed loop driver supplied as a set
· Stator: laminated silicon steel core, 2-phase winding
· Rotor: permanent magnet plus toothed iron caps (hybrid type)
· Encoder: rear-shaft mounted, incremental or absolute
· Bearings: ball bearings rated past 20,000 hours
Stepper motor and servo motor manufacturer in Changzhou, China since 2004. We run 5 production lines with annual output over 1,000,000 motors, serving OEM customers in 30+ countries.
About Us facility Solutions CertificationsA closed loop stepper motor is a standard hybrid stepper with an encoder added to the shaft and the position loop closed around it. The driver constantly compares where the controller commanded the shaft to be against where the encoder says it actually is, then corrects the difference. The result is a motor with the simple step/direction wiring of a stepper but the position reliability of a servo. It keeps a 1.8° step angle and runs in open-loop fashion until the load pushes it off target, at which point the feedback takes over.
In a plain open-loop stepper, if the load torque exceeds what the motor can hold at that speed, the rotor skips to the next position — a lost step — and the controller never knows. A closed loop stepper motor catches that. The encoder reports the actual position, the driver sees the error build, and it adds current or steps in real time to bring the rotor back on target. The controller stays in sync with the real shaft position, so the toolpath or placement stays accurate even when the load changes.
Both use encoder feedback, but they're built differently. A closed loop stepper keeps the high pole count of a stepper, so it has strong holding torque at standstill and low speed, and it doesn't hunt at rest — good for hold-and-index jobs. An AC servo motor shines at high speed and high dynamic response, with smoother torque across a wide speed range. For most positioning work that just needs anti-lost-step reliability, a closed loop stepper does the job at lower cost; step up to a servo when speed and dynamics lead.
Yes. A closed loop stepper motor runs on a matched closed loop stepper driver or controller that reads the encoder and closes the position loop — a plain open-loop driver can't use the feedback. We supply the motor and driver as a tested set, with commutation and basic tuning done before shipping, so you don't have to pair them yourself.
Frame sizes run NEMA 23 (57mm), NEMA 24 (60mm), NEMA 34 (86mm), and NEMA 42 (110mm), all at 1.8° step angle. The NEMA 23 closed loop stepper motor is our most-asked frame; the larger sizes cover higher-torque axes. Holding torque spans 0.3 N·m to 12 N·m. Standard encoder is a 1000-line incremental; higher-resolution and absolute encoders are available. Each NEMA size has its own page with the full model-by-model spec table.
Yes. Encoder resolution and type (incremental or absolute) are selectable. Shaft diameter, length, and end type are made to your drawing, and we match winding voltage and current to your driver. A gearbox or brake can be mounted and tested together with the closed loop unit before it ships.
A working reference for engineers and procurement teams deciding between open-loop steppers, closed loop steppers, and servos. It covers how the feedback loop works, what it fixes, the driver it needs, and how to tell whether your application actually calls for one.
A closed loop stepper motor is a hybrid stepper with an encoder on the shaft. The encoder reports the rotor's actual position; the driver compares that against the commanded position and acts on the difference. If the rotor falls behind — because the load grew, the move was too fast, or there was a sudden disturbance — the driver adds current or steps in real time to pull it back on target. Below the error threshold the motor behaves like a normal stepper and draws only the current it needs, which also keeps it cooler and quieter than an open-loop motor running at full current all the time.
The whole point of the feedback loop is lost-step protection. In an open-loop system, when required torque exceeds holding torque at that speed, the rotor skips to the next stable position. Each skip is unaccounted error — and the controller has no way to know it happened. On a CNC router the toolpath drifts and the part is scrapped; on a pick-and-place head the placement misses. The operator only finds out after the damage is done. A closed loop stepper motor removes that failure mode entirely: the encoder sees the rotor lagging and the driver corrects before the error accumulates.
| Open Loop Stepper | Closed Loop Stepper | AC Servo | |
|---|---|---|---|
| Feedback | None | Encoder | Encoder |
| Lost steps | Possible | Corrected | None |
| Holding torque at rest | High | High | Lower, can hunt |
| High-speed performance | Drops off | Better than open loop | Best |
| Heat / efficiency | Full current always | Current matched to load | Current matched to load |
| Cost | Lowest | Middle | Highest |
The closed loop stepper sits between the two: it removes the open-loop motor's biggest weakness without the cost and tuning of a full servo. For hold-and-index motion that just can't afford a missed step, it's usually the right call.
A closed loop stepper motor needs a matched closed loop stepper driver — the driver reads the encoder and closes the position loop, which an open-loop driver can't do. Standard feedback is a 1000-line incremental encoder; for finer resolution or position memory through a power cut, an absolute encoder is the option. Two things worth confirming at selection:
Don't over-engineer. An open-loop stepper is fine for steady, known loads at moderate speed. Reach for a closed loop stepper motor when one or more of these is true:
Send us the load, the speed target, and the accuracy you need, and our engineers confirm the frame, torque, and encoder before you order.
The anti-lost-step reliability makes these motors a fit for desktop and benchtop CNC, pick-and-place heads at low to moderate speed, light automation and assembly lines, AGV steering and gripper mechanisms, and stage lighting or camera pan-tilt rigs. Smaller frames (NEMA 23–24) handle precision axes; larger frames (NEMA 34–42) take the higher-torque axes that can't tolerate a missed step.
