KRS-3304R2 ICS



6pcs set  No.03171  Open

18pcs set No.03172 Open


 Max Torque: 13.9kg・cm
 Max Speed: 0.11s/60deg.

 Max Torque: 11.2kg・cm
 Max Speed: 0.13s/60deg.

 Size: 32.5×26×26mm
            (Excluding protrusions)
 Weight: 33.7g
 Maximum operating angle: 270°(±135°)
 Gear: Metal gear
 Case: Plastic
 Gear ratio: 289.22:1
 Power-supply voltage: LV(6-7.4V)
 Cable: Detachable
 Connector: ZH connector

 Communication standard: ICS3.6 (Serial/PWM)
 Baud rate: 115200/625000/1250000bps
 Initial setting: Normal mode(Serial/PWM both)
 Signal level: TTL
 Rotation mode: Possible

<Supported control board>

 Dual USB Adapter HS
 ICS USB Adapter HS

 ZH connection cable A (300mm)  1pcs
 ZH connection cable B (300mm)  1pcs
 M3-6 Low head screw for servo horn  1pcs

   6pcs set
 ZH connection cable A (300mm)  6pcs
 ZH connection cable B (300mm)  6pcs
 M3-6 Low head screw for servo horn  6pcs

   18pcs set
 ZH connection cable A (300mm)  18pcs
 ZH connection cable B (300mm)  18pcs
 M3-6 Low head screw for servo horn  18pcs


Made in Japan

Product Description

KRS-3304R2 ICS is a small servo of cube type design. Since this servo employs a high output coreless motor, it outputs a maximum torque of 13.9 kgf · cm (at 7.4 V). To secure the durability when using it with a biped walking robot, we adopted a metal gear.

KRS-3304R2 adopted ICS 3.6. In ICS 3.6, commands for acquiring the current value are prepared. Since you can read the current value in the same way as the command to read the stretch and speed, it is convenient when controlling the servo with the program.



[Product Specifications]

Gear: Metal gear
Since all gears are metal, it has sufficient durability.
By supporting the shaft of the final gear with a bearing, stable operation has been realized.

Case: KRS 3300 Series

The cubic shape allows the case to be oriented in any direction without significantly altering the silhouette. It will not negatively affect the robot’s style. There is minimal surface variation for easy frame design and mounting.

*The repair parts case is the "Servo Case for KRS 3301". Please note that Servo Case for KRS 3300 Series cannot be used.

Wiring: 2 ZH connectors
The cable is removable, so you can replace it with cable of the length you prefer. Two connectors have been mounted, so servo motors can be connected to each other for beaded multi-drop connection.

Communication specifications: ICS3.6
ICS3.6 is upward compatible with ICS3.5. A command for acquiring the current position has been added to the 3.5 version content.For the communication format, you can select between serial and PWM, the same as before. Servo motor communication can be changed based on the microcomputer board used for control. Also, in serial mode, IDs can be assigned to the servo motors, so multi-drop communication in which the servo motors are connected is possible.


KRS-3301/3302/3304/3304R2 can be intermixed.
When used with multi-drop connection, the various models in the KRS 3300 Series can be intermixed. KXR Series parts can also all be used in common.(The output shaft differs depending on the fixed portion, so consult with the assembly manuals.)




*The product is a 6-7.4V servo motor. HV batteries cannot be used.

*When used in combination with RCB-4HV/3HV and Ni-MH5 cells (6V) or Li Fe2 cells (6.6V), use Booster 3.1 (booster circuit). When Li Po2 cells (7.4V) are used, this is not necessary. It also is not necessary with RCB 4mini.

  Booster3.1 for RCB-4HV
 Booster3.1 for RCB-3HV

*The communication mode at shipment is Normal Mode, so you can switch between serial mode and PWM mode depending on the high/low of the signal wire after powering up. When used with RCB4, it is automatically recognized to be in serial mode. Use the product after assigning it to a servo motor ID number. For details on communication specifications, refer to the Software Manual.
When used with serial-only (PWM prohibited), switch using the Dual USB Adaptor HS sold separately.


    About KRS Servo Motor Communication Modes

*For the securing screws on the free horn side, use a 2.6-4 flat head screw. If a 2.6-6 flat head screw (included with KHR-3HV, etc) is used, they may pierce the case and break the base.


*To secure the frame to the upper case, use 2 mm screws.



[Control method]

Control from the control board "RCB-4"


You can easily control the servo by combining RCB - 4 HV or RCB - 4 mini with Motion Creation Software HeartToHeart 4.

RCB-4HV has 2 lines for servo control, 10 ports for analog sensor and 10 ports for digital I/O terminal are prepared.

RCB-4 mini is compactly designed for small robots. 2 lines for servo control and 5 ports for analog sensor terminals can be used. The PIO terminal is not mounted.

Using HeartToHeart4, you can create motion and adjust the robot. Motion can be created by arranging controls (panels) with various functions. You can create a simple "greeting" motion, etc. You can also create complex motions such as sensors and wireless controller buttons.

01 05 03

By assigning ID numbers to each servo and making multi-drop connection, devices are connected and communicate.


  RCB-4HV or RCB-4mini
  Dual USB Adapter HS
  LV Power Switch Cable



Control from PC


By using the Dual USB adapter HS you can control the servo directly from the PC. Please send the command referring to the published "Software manual (command reference)". Communication methods and samples are also published, so please see the following article for details.

 『シリアルサーボ制御方法(4) PCから直接制御編(その1)』

 『シリアルサーボ制御方法(5) PCから直接制御編(その2)』



  Dual USB Adapter HS



Control from Microcomputer board or PC board


ICS devices such as KRS servo can be controlled from the UART terminal of the commercial board. ICS has the Tx (transmit) and Rx (receive) signal lines of the ICS device are integrated, it was necessary to prepare the circuit when connecting to the UART terminal. Circuits necessary for communication are prepared on this conversion board. You can communicate with the ICS device simply by connecting each terminal to the board. Please refer to "Software manual (command reference)" about communication method and command.

 『シリアルサーボ制御方法(2) ICS編』

 『シリアルサーボ制御方法(3) ソフト編』




  ICS conversion board shield
  LV Power Switch Cable

*When using with Arduino UNO
  KSB Shield 2


 We released a library for Arduino. Please download it from the link below.

 『ICS Library for Arduino ver.2』


 For detailed usage of the Arduino library, please see this article.

 『ICS変換基板の使用方法(1) 準備編』

 『ICS変換基板の使用方法(2) サーボ制御編』

 『ICS Library for Arduino のver.1.0とver2.0の違いについて』



Serial Manager

You can set the servo ID and communication speed by using the ICS 3.5 / 3.6 Manager software. Various parameters such as "stretch" and "speed" can be changed.

 ICS3.5/3.6 Manager software R1.1.0.0



[Power supply]

For LV servo, please use 2 cell (6.6 V) lithium ferrite battery(Li-Fe).

500x500-F2-850 500x500-F2-1450

  ROBO Power Cell F2-850 type (Li-Fe)

  ROBO Power Cell F2-1450 type (Li-Fe)

*Handling the battery requires caution.Please read this article before using.


6-cell (7.2 V) battery of Ni-MH can also be used.


ROBO Power Cell E-type 6N-800mAh (Ni-MH)



51202 51203 51204

  BX-20LF(only for Li-Fe) 

  BX-31LF(only for Li-Fe)

  BX-32MH(only for Mi-MH)

*BX-31LF / 32MH can not be charged from the PC's USB terminal. Please do not connect charger to PC. Please use the AC adapter (2A recommended) to be used for charging the smartphone etc.


AC Adapter

For robots with fewer servos mounted like arm type, you can use the following AC adapter. Be careful of the current capacity when using it.


AC Adapter(6V2A)


Information on KRS servo is prepared collectively in "ICS · KRS Servo Development Material". In addition, we also have various information on robots in "Technical Guide", so please refer to it.