FUTABA RS204MD User manual

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1M23Z06502
User’s Manual Ver.1.04
RS204MD
Command Type Servo for Robot
Instruction Manual
Caution
・Read this instruction manual before use.
・Keep this manual handy for immediate reference.
For models

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1. FOR SAFETY .......................................................................................................................................... 5
WARNING SYMBOLS................................................................................................................................................5
CAUTIONS FOR USE................................................................................................................................................5
CAUTIONS FOR STORAGE........................................................................................................................................6
2. INTRODUCTION...................................................................................................................................... 7
COMPONENTS.........................................................................................................................................................7
FEATURES .............................................................................................................................................................8
●Small and Lightweight .......................................................................................................................................8
●Interactive High-Speed TTL Communication ...................................................................................................8
●Servos for Both Command Type and PWM Type ..............................................................................................8
●Feedback(Only as Command Type) ..........................................................................................................................8
●Compliance Control ............................................................................................................................................8
●Calibration ..........................................................................................................................................................8
●Wiring from the Output Shaft............................................................................................................................8
●Horn with a mark for the reference position.....................................................................................................8
PART NAMES /HANDLING INSTRUCTIONS ............................................................................................................9
HOW TO ATTACH THE SERVO.................................................................................................................................10
PIN ASSIGNMENT OF THE CONNECTOR ................................................................................................................11
COMMUNICATION SETTINGS ................................................................................................................................11
DEFINITION OF ANGLE AND ITS RANGE................................................................................................................14
●Definition of “0 degrees” and operational range............................................................................................14
●Dead Zone(undetectable range) .......................................................................................................................14
3. CONNECTIONS...................................................................................................................................... 15
SYSTEMS ..............................................................................................................................................................15
●Systems as Command-Type Servos .................................................................................................................15
●Systems as PWM Type Servos .........................................................................................................................16
NOTES OF CONNECTION.......................................................................................................................................17
4. CONTROL ............................................................................................................................................... 19
ABSTRACT ............................................................................................................................................................19
●Switch of Command-Type and PWM-Type ......................................................................................................19
●Communication Protocol (TTL Command-Type).............................................................................................19
●Control as PWM-Type Servos...........................................................................................................................19
●Memory Map .....................................................................................................................................................20
●Servo ID ............................................................................................................................................................20
●Packet................................................................................................................................................................20
●Short Packet.................................................................................................................................................20

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●Long Packet..................................................................................................................................................20
●Return Packet ..............................................................................................................................................20
FORMAT OF PACKETS............................................................................................................................................21
●Short Packet......................................................................................................................................................21
●Long Packet ......................................................................................................................................................25
●Return Packet ...................................................................................................................................................27
MEMORY MAP ......................................................................................................................................................28
4.1. Invariable ROM Area..............................................................................................................................28
●No.0/No.1 Model Number(2 Byte, Hex, Read) ............................................................................................28
●No.2 Firmware Version(1Byte, Hex, Read) ...................................................................................................28
4.2. Variable ROM Area .................................................................................................................................29
●No.4 Servo ID (1Byte, Hex, Read/Write) .....................................................................................................30
●No.5 Servo Reverse(1Byte, Hex, Read/Write) .............................................................................................30
●No.6 Baud Rate(1Byte, Hex, Read/Write) ...................................................................................................30
●No.7 Return Delay(1Byte, Hex, Read/Write) ..............................................................................................31
●No.8/No.9/No.10/No.11 Angle Limit (2 Byte, Hex, Read/Write)......................................................................32
●No.14/ No.15 Temperature Limit(2 Byte, Hex, Read) ..................................................................................32
●No.22 Torque in Silence(1 Byte, Hex, Read/Write, for PWM) ....................................................................33
●No.23 Preparation Time (1 Byte, Hex, Read/Write, for PWM)...................................................................33
●No.24 / No.25 Compliance Margin (1 Byte, Hex, Read/Write) ........................................................................34
●No.26 / No.27 Compliance Slope (1 Byte, Hex Read/Write) ............................................................................34
●No.28 / No.29 Punch (2 Byte, Hex, Read/Write) ..............................................................................................34
4.3. Variable RAM Area .................................................................................................................................36
●No.30 / No.31 Goal Position (2 Byte, Hex, Read/Write）............................................................................37
●No.32 / No.33 Goal Time (2 Byte, Hex, Read/Write）.....................................................................................37
●No.35 Maximum Torque (1 Byte, Hex, Read/Write) ...................................................................................38
●No.36 Torque Enable (1 Byte, Hex, Read/Write）...........................................................................................38
●No.38 PID Coefficient (1 Byte, Hex, Read/Write）.......................................................................................39
●No.42 / No.43 Present Position (2 Byte, Hex, Read) ...................................................................................39
●No.44/No.45 Present Time (2 Byte, Hex., Read) .............................................................................................40
●No.46/No.47 Present Speed (2 Byte, Hex, Read).............................................................................................41
●No.48/No.49 Present Current (2 Byte, Hex, Read)..........................................................................................42
●No.50/No.51 Present Temperature (2 Byte, Hex, Read) .............................................................................43
●No.52/No.53 Present Voltage (2 Byte, Hex, Read) ......................................................................................44
5. REFERENCES ........................................................................................................................................ 45
SPECS ...................................................................................................................................................................45
.DIMENSIONS.......................................................................................................................................................45
●RS204MD ..........................................................................................................................................................46
●Dimensions with Servo Horn and Free Horn..................................................................................................47

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●Servo Horn and Free Horn for RS20x/RS30x ..................................................................................................48
OPTION PARTS......................................................................................................................................................49
HOW TO USE “BRACKET”......................................................................................................................................51
●Fixing Brackets to RS204MD...........................................................................................................................51
●Jointing Other Parts/Servos.............................................................................................................................51
●Usage of Brackets .............................................................................................................................................52
●Dimensions with Brackets ...............................................................................................................................52
DIMENSIONS OF TERMINAL BOARD......................................................................................................................53

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1. FOR SAFETY
To use this product safely, please pay your full attention to the followings.
Be sure to read this instruction manual prior to using this product.
Warning Symbols
The warning symbols used in this text are defined as follows:
Indication Meanings
Danger Indicates a hazard that will cause severe personal injury, death,
or substantial property damage if the warning is ignored.
Warning Indicates a hazard that can cause severe personal injury, death, or substantial
property damage if the warning is ignored.
Caution Indicates a hazard that will or can cause minor personal injury, or property
damage if the warning is ignored
Symbols: :Prohibited :Mandatory
Cautions for Use
Caution
Do not disassemble or alter the servo.
Otherwise, it may cause breakage in the gear box, fire on the servo or explosion of
the battery.
Do not use any battery as a power supply other than the specified battery.
The product is designed to be operated by Futaba’s 9.6V Ni-MH battery only. Do not
use any other batteries.
Do not touch the servo case during or some time after operating the servo.
Otherwise, you may get burned on the finger as the motor or electronic circuit in the
servo gets very hot.
Do not let the servo get covered with sandy dust or water.
Otherwise, the servo may stop moving or have a short circuit. The servo is not
designed to be waterproof or dust-proof.

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Do not use this product for any application other than indoor hobby-robots.
Futaba is cleared of all responsibility to the results caused by the usage of this
product for any application other than indoor hobby-robots.
Do not turn the servo horn forcibly.
Otherwise, the servo will be damaged.
Do not leave the servo locked.
If the servo continues to be locked due to a strong external force, it may cause smoke,
fire or damage.
Cautions for Storage
Caution
Do not store the servos in the following conditions.
Places where the temperature is over 60℃or below －20℃.
Places where the Sun directly shines over the servos.
Places where it is very high in humidity.
Places where there is a strong vibration.
Places where there is a lot of dust.
Places where static electricity tends to be induced.
Places where infants can reach.
◆Storing the servos in the places shown above may cause deformation and failure of the servos, or
hazard.

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2. Introduction
Components
The following parts are included in RS204MD.
Please refer to p.50 “Optional parts”for optional parts and repair parts.
●1) Servo(RS204MD) x1
2) Servo Horn x1
3) Screw to fix servo horn x1 (M2x8 Tapping Screw)
*Servo Horn and Screw are attached to the servo.
●4) Cable (ADH-Connector, 70mm) x1
●5) Free Horn (Same as for RS30x) x1
●5) USAGE PRECAUTION x1

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Features
RS204MD is specially designed for robotic applications, having the following features.
●Small and Lightweight
RS204MD is small and lightweight servos specially designed for robots, which are 12g respectively.
●Interactive High-Speed TTL Communication
TTL bi-directional communication of a maximum baud rate of 230kbps is possible and is
used for the communication between the robot’s processor and servos.
●Servos for Both Command Type and PWM Type
RS204MD can be controlled either as the Command Type Servo for robots or the PWM Type Servo for
existing R/C servos. The type is automatically switched by the first signal sent after these products are
connected.
●Feedback(Only as Command Type)
Information of sensors on the servo such as the position, load, temperature, electric current, and the
alarm situation, etc. can be obtained via TTL communication.
●Compliance Control
With this feature, the movement of the RS204MD is controlled in accordance with the distance between
the present and target positions. This enables the robot to move very smoothly without trembling its
arms and legs and to absorb turbulence from an external force.
●Calibration
Angular position of every servo is calibrated by our standard gauge before their shipment. Even if
another RS204MD servo is employed, it does not require any bothersome work for adjusting its angular
position.
●Wiring from the Output Shaft
In order to avoid wires becoming entangled during operation, they are drawn out from the rear of the
output shaft. Another shaft is installed on the bottom case to make the center impeller structure easy to
construct.
●Horn with a mark for the reference position
凹marks are placed on the circumference of the servo horn in order to make sure the reference position
even after being built in. (one 凹for 0°position, two 凹s for 90°position, three 凹s for 180 position
and four 凹s for 270°position)

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Part Names / Handling Instructions
Fig. 2.1 Part Names
Caution
Do not remove screws to fix cases of the servo unless repair or replacement is needed.
When removing all case fixing screws, be careful not to get dust or foreign matter inside the case.
Route the cable through the free horn hole in the bottom case when using the Inward-Connector.
Bending cables strongly will cause disconnection and/or short circuit.
Output-Axis
Screw to fix cases of the servo
Free Horn
Servo Horn
Connector(Outward)
Connector (Inward)
Screw to fix cases of the servo and other parts.

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How to attach the servo
Remove some of the screws of RS204MD and use its hole to fix the servo to brackets or other frames.
Refer Fig. 2.2 for the depth of each hole.
1.8mm from each Reference-Surface of Hole (A) is Clearance Hole.
Fig. 2.2 Screw Depth
Fig. 2.3 Reference for the length of the screw to fix other parts.
Other Parts (Plate)
t=1.0mm
Hole to fix cases and other parts.
Screw Depth: up to 7mm from each Reference-Surface
*1.8mm from each Reference-Surface is Clearance Hole.
Hole to fix other parts.
Screw Depth: up to 2.5mm
Tapping Screw:1.2×5mm
(Option No.BS3472)
Tapping Screw : 1.2×3.5mm
(Option No.BS3471)
Do NOT
remove
Reference-Surface
Reference-Surface