Smart servo actuator
Feetech SCS series (TTL serial bus) smart servo actuator
Lower-voltage TTL serial-bus servos for 6 V to 8.4 V supplies, from 4.5 kg·cm (0.44 Nm) to 40 kg·cm (3.9 Nm) stall torque (series maximum), including double-shaft versions for robot joints.
Key specifications
| Voltage (max) | 8.4 V |
|---|---|
| Data / bus | TTL half-duplex serial bus |
| Peak torque (max) | 3.9 Nm |
| Supply | 6 V, 7.4 V and 8.4 V models |
| Stall torque | 4.5 to 40 kg·cm (0.44 to 3.9 Nm) by model |
Summarised in our own words from Shenzhen Feetech RC Model Co., Ltd.'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Listing page read (11 models, SC-4000 to SC-2332); per-model speeds and feedback type not recorded.
Specify Motion is not affiliated with Shenzhen Feetech RC Model Co., Ltd.. Feetech and SCS series (TTL serial bus) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a Feetech part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 3 series from our supply network are the closest match on published figures.
Kinco's current-generation AC servo motor line, matched to the JD2 and FD5P PRO drives. Small-inertia 40-80 mm frames run at 3000 rpm on 220 V; large-inertia 130 and 180 mm frames are 1500 rpm machines reaching 47.8 Nm rated and 7.5 kW, with 23-bit multi-turn absolute encoders as standard.
| Published maximum | SCS series (TTL serial bus) | SMK Series AC Servo Motors (SMK40S/60S… |
|---|---|---|
| Rated torque | — | 47.8 Nm |
| Peak torque | 3.9 Nm | 119.5 Nm meets or exceeds |
| Speed | — | 6,000 rpm |
| Power | — | 7,500 W |
Leadshine low-voltage PMSM servo motors from a 25 mm 33 W unit up to a 130 mm 2 kW unit, wound for 24-60 V DC buses. Fully published data covers torque to 6.4 Nm rated / 16 Nm peak, 17-bit absolute or 2500 ppr incremental encoders and IP65. Designed for ELD2, 2ELD2 and ELD3 drives.
| Published maximum | SCS series (TTL serial bus) | ELVM Series Low-Voltage DC Servo Motors |
|---|---|---|
| Rated torque | — | 6.4 Nm |
| Peak torque | 3.9 Nm | 16 Nm meets or exceeds |
| Speed | — | 6,000 rpm |
| Power | — | 2,000 W |
Leadshine motor-plus-drive units from 200 to 750 W on 24-48 VDC, with 17-bit magnetic encoders, CANopen or Modbus/pulse control and up to 300% overload, published in the Leadshine low-voltage DC catalogue.
| Published maximum | SCS series (TTL serial bus) | iSV2 Integrated Low-Voltage Servo Motors |
|---|---|---|
| Rated torque | — | 2.39 Nm |
| Peak torque | 3.9 Nm | 7.2 Nm meets or exceeds |
| Speed | — | 4,000 rpm |
| Power | — | 750 W |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What a smart servo actuator is
A smart servo actuator packages a small DC or brushless motor, a gear train, a position sensor and a microcontroller with motion control in one compact module. Each module is addressed on a shared serial bus, typically TTL or RS485, and can be commanded in position, velocity or current modes, with feedback on position, load, voltage and temperature. Units daisy-chain so multiple joints share one cable. They are widely used for robot joints in research, education and light service robots.
When engineers choose a smart servo actuator
Choose a smart servo for lightweight robot arms, grippers, humanoids and research platforms where quick integration and many networked joints matter more than industrial ratings. They are compact and simple to wire. The trade-offs are torque, precision and life: plastic or small metal gearing has backlash and limited torque, and duty cycles are lower than industrial servos. For production machines with heavy duty, an industrial servo with a gearbox is more appropriate.
How to specify the Feetech SCS series (TTL serial bus)
Send these with your enquiry and an engineer can confirm the right SCS series (TTL serial bus) variant or an equivalent:
- Stall and continuous torque (Nm)
- No-load speed (rpm)
- Supply voltage (V)
- Communication bus and protocol
- Position resolution and range
- Gear material and backlash
- Mass and form factor (g, mm)
Common mistakes to avoid
- Designing to stall torque instead of continuous working torque
- Ignoring gear backlash and compliance at the end of an arm
- Daisy-chaining too many joints on one power line
- Assuming industrial duty life from hobby-grade gearing
Feetech SCS series (TTL serial bus): frequently asked questions
What is the Feetech SCS series (TTL serial bus)?
Lower-voltage TTL serial-bus servos for 6 V to 8.4 V supplies, from 4.5 kg·cm (0.44 Nm) to 40 kg·cm (3.9 Nm) stall torque (series maximum), including double-shaft versions for robot joints. Published series figures include voltage 8.4 V, peak torque 3.9 Nm. It is made by Shenzhen Feetech RC Model Co., Ltd.; Specify Motion can help source it or propose an equivalent.
Who makes the Feetech SCS series (TTL serial bus)?
The Feetech SCS series (TTL serial bus) is made by Feetech (Shenzhen Feetech RC Model Co., Ltd.) and is listed here for engineers comparing options. Specify Motion is not affiliated with Shenzhen Feetech RC Model Co., Ltd.; brand names are used only to identify the product.
What is the voltage of the Feetech SCS series (TTL serial bus)?
The published series maximum voltage is 8.4 V. Individual models and sizes in the SCS series (TTL serial bus) range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Feetech SCS series (TTL serial bus)?
Yes. On published figures, Kinco SMK Series AC Servo Motors (SMK40S/60S/80S, SMK130G, SMK180G) and Leadshine ELVM Series Low-Voltage DC Servo Motors are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the difference between a smart servo and an RC servo?
An RC servo is controlled by a pulse width signal and gives no feedback. A smart servo has an onboard controller on a digital bus, so it can report position, load, temperature and voltage, accept different control modes and be daisy-chained. This makes smart servos much better suited to robotics.
Are smart servos suitable for industrial machines?
Smart servos are typically designed for robotics research, education and light service robots. For heavy-duty production machines, industrial servo motors with gearboxes and drives give higher torque, precision and life, along with recognised safety functions. Smart servos can still suit light industrial tasks with modest duty.
Further reading: How to select an integrated servo motor · How to select a servo motor · Servo and stepper motors
Other smart servo actuator series
Spec builder
Specify what you need instead of SCS series (TTL serial bus)
Select every part you need, answer the questions an applications engineer would ask, and see your summary before we ask for any details.
- 1Products
- 2Performance
- 3Environment
- 4Volumes
- 5Your spec
Engineer support
Let our experienced engineers do the hard work for you
Tell us how you use the Feetech SCS series (TTL serial bus): the load, speed, duty and environment. Our engineers will confirm whether it is still the right part, find it for you, or propose an alternative that fits better.
- Reviewed by an engineer, not an autoresponder
- Like-for-like and better-fit alternatives
- Standard, modified and custom options
Prefer to configure it? Use the spec builder.