FUTABA RS301CR User manual

RS301CR/RS302CD
Command Type Servo for Robot
Instruction Manual
Caution
 Read this instruction manual before use.
 Keep this manual handy for immediate reference.
For models
User’s Manual Ver.1.0

2
CONTENTS
１．FOR SAFETY
●WARNING SYMBOLS ............................................................................................. 4
●CAUTIONS FOR USE ............................................................................................. 4
●WARNINGS IN HANDLING BATTERIES ............................................................. 5
●Cautions for Storage ................................................................................................. 5
２．INTRODUCTION
● Features .................................................................................................................... 6
● Part Names / Handling Instructions ........................................................................ 7
３．CONNECTION
● System Configuration ............................................................................................... 8
● Pin Assignment ...................................................................................................... 8
● Cautions when connecting ....................................................................................... 9
４．CONTROL METHOD
● Abstract ................................................................................................................... 10
● Packet Format ......................................................................................................... 11
Short Packet ............................................................................................... 11
Long Packet ................................................................................................ 14
Return Packet ............................................................................................. 15
● Memory Map ........................................................................................................... 17
● Invariable ROM area .............................................................................................. 17
No.0 /No.1 Model Number ............................................................. 17
No.2 Firmware Version ................................................................. 17
● Variable ROM area ................................................................................................. 18
No.4 Servo ID ................................................................................ 19
No.5 Servo Reverse ........................................................................ 19
No.6 Baud Rate .............................................................................. 19
No.7 Return Delay ...................................................................... 20
No.8 /No.9 /No.10 /No.11 Angle Limit ........................................... 20
No.14 /No.15 Temperature Limit .................................................. 20
No.24 /No.25 Compliance Margin ................................................. 21

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No.26 /No.27 Compliance Slope .................................................... 21
No.28 /No.29 Punch ....................................................................... 21
● Variable RAM Area ................................................................................................. 23
No.30 /No.31 Goal Position ............................................................ 24
No.32 /No.33 Goal Time ................................................................. 24
No.35 Maximum Torque ................................................................ 24
No.36 Torque Enable ..................................................................... 25
No.42 /No.43 Present Position ....................................................... 25
No.44 /No.45 Present Time ............................................................ 26
No.46 /No.47 Present Speed .......................................................... 26
No.48 /No.49 Present Load ........................................................... 27
No.50 /No.51 Present Temperature .............................................. 28
No.52 /No.53 Present Voltage ....................................................... 29
５．REFERENCE
● SPECIFICATIONS ................................................................................................. 30
● DIMENSIONS ........................................................................................................ 31
● TROUBLESHOOTING ........................................................................................... 32

4
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 Meaning
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.
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.
1.FOR SAFETY

5
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.
Warnings in Handling Batteries
Warning
Do not use any battery charger other than the specified charger.
Otherwise, the battery may be get damaged, fire, smoke or liquid leakage. Be sure to
use batteries recommended by Futaba.
Do not use battery packs connected in parallel.
Connecting battery packs in parallel may cause abnormal heat generation or
explosion due to the differences between charging voltages.
Do not disassemble or alter battery packs.
Otherwise, it may cause fire, explosion or liquid leakage. And please be aware that
such battery packs will be no longer guaranteed even if their warranties are not
expired.
Do not use batteries if any abnormal symptoms are seen.
If you find any abnormal symptoms such as cracks in coating film, abnormal heat
generation from batteries or deformation of batteries, never use the battery because
it may cause serious consequences.
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.

6
2.INTRODUCTION
Features
RS301CR/RS302CD servo is especially designed for robotic applications, having the
following features.
● Small and Lightweight
RS301CR and RS302CD are small and
lightweight servos specially designed for
robots, which are 28g and 21g
respectively.
● Interactive high speed
RS485 communication
RS485 half duplex communication
carries out bidirectional high-speed
communication up to 460kbps. RS485 is
used for the communication between the
robot’s processor unit and servos at very
high speed.
●Command type control
The servo can be controlled by commands
sent from the robot’s processor unit
through RS485. And a single command can
convey multiple data, including a period of
time to move and a target position. This
relieves the robot’s processor unit from load
significantly.
●Data Feedback
Various kinds of information about the
servo such as angular position, load,
temperature, current and alarm can be
obtained via RS485.
●Compliance control
With this feature, the movement of the
RS301CR/RS302CD 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 external force.
●Calibration
Angular position of every
RS301CR/RS302CD servo is calibrated by
our standard gauge before their shipment.
Even if another RS301CR/RS302CD servo
is employed, it does not require any
bothersome work for adjusting its angular
position.
● 12bit-A/D converter
for precise positioning
Angular feedback using the 12bit-A/D
converters makes it possible to position the servo
angle precisely.
● Wiring from the output shaft
Wires pass through the backside of the
output shaft to avoid getting wires
entwined in operation.
● Horn with a mark for 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 for 90°, three for 180°
and four for 270°）.

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Part Names / Handling Instructions
Removing the screws for fixing the servo with a case may damage the servo.
Fig.2.1 Part names
Output-axis
Screws for fixing
the servo to a case
※Do not remove
these screws.
Caution
Connecter

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3.CONNECTION
System Configuration
The following figure shows a robotic system using RS301CR/RS302CD servos, RPU-10
processor unit and etc.
Fig. 3.1 Robotic system configuration
Pin Assignment
Pin assignment of the RS301CR/RS302CD servo is shown below.
Fig. 3.2 Pin assignment
① Gray ：RS485(D-)
② Black ：RS485(D+)
③ Gray ：VCC(7.4V)
④ Black ：GND
②④
①③
RS301CR
RS302CD
Motion editor
Control softwar
Processing Unit
(
RPU-10 etc.）
RSC-U485
Battery
(
PR-4S780P
)

9
Cautions when Connecting
Please refer to the figure below for connecting RS301CR/RS302CD and RPU-10.
Fig. 3.3 Operating with RPU-100
Allowable current for relay connectors is 2A and for servo harness is 3A each for continues use.
Set your PC’s communication parameters as follows;
Baud rate ：115.2 bps
（adjustable between 9.6kbps and 460kbps, Refer to Table 4.6 Baud rate in p.19）
Data bit length ：8 bits
Parity ：none
Stop bit ：1 bit
Flow control ：none
RPU-10
PC
Please prepare it by your self
Relay box
RS301CR/RS302CD
RS232C
PR-4S780P

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4.CONTROL METHOD
Abstract
●Communication Protocol
The communication protocol of the RS301CR/RS302CD servo is based on RS485
(IEEE485) half duplex communication. Data transmission and reception are carried out
alternatively on the same signal line.
Normally, the RS301CR/RS302CD servo stands by in reception mode. But, when it
receives from RPU-10 a command to send the servo’s data and status, it switches to
transmission mode, sends them out and finally returns to reception mode.
●Memory Map
The RS301CR/RS302C servo has its own memory area to store data necessary for its
movement. This memory area is called “Memory Map”.
This memory map is divided into two groups. One is “RAM area” in which data will be
erased when the power is turned off. The other one is “ROM area” in which data is held
even after the power is turned off.
●Servo ID
You can set ID numbers to RS301CR/RS302C servos individually.
These ID numbers are used to identify servos during communication. The default
number of every servo is set to “1”. When you use multiple servos in a single
communication network, give them different ID numbers.
●Packet
A packet is a block that is used for sending a command to or receiving data from
RS301CR/RS302C servos. Packets are divided into the following three groups, having
different formats.
(1) Short Packet(→p.11)
Short packets are used for sending the data in the memory map toward a single servo.
(2) Long Packet(→p.14)
Long packets are used for sending the data in the memory map toward multiple servos
simultaneously.
(3) Return Packet(→p.16)
This is a packet that is sent from a servo when a return packet is requested.

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Packet Format
●Short Packet
Short packets are used for sending the data in the memory map toward a single servo.
Packet structure
This is a line head of a packet. FAAFH is used for short packets.
“xH” denotes Hexadecimal number.
This is a servo’s ID. The valid numbers are from 1 through 127 (00H ~ 7FH). When ID is set to 255,
commands are commonly effective to all servos. The processor unit cannot obtain any data from servos
at this time.
Each bit has the following meaning.
Table 4.1 Send packet flags
Bit Function
7 Reserved
6 Write in Flash ROM
5 Reboot servo
4 Initialize memory map data
3
2
1
0
Return-packet’s address
Bit7：Reserved
Set this bit always at “0.”
Bit6：Write in Flash ROM
Setting this bit to “1” (Flags=40H) and sending a packet of address=FFH, length = 00H
and count = 00H to a servo will write the data of the memory map from No.4 through
29(04H~1DH) into the non-volatile Flash ROM. It takes about 1 second for writing.
Header ID
Flags
Address
Length Count
Data
Sum
Header
ID
Flags

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Ex）Write the data of the ID1 servo into the Flash ROM.
Hdr ID Flg Adr Len Cnt Sum
The servo’s memory should be renewed with the data you want to write into the Flash
ROM by transferring the data by using a short packet beforehand.
The servo ID becomes effective only after receiving a packet. The ID returns to the
previous number on the next boot up unless the ID is written into the Flash ROM.
Never turn off the power while the Flash ROM is being written.
Bit5：Reboot servo
Setting this bit to “1” (Flags=20H) and sending a packet of address=FFH, length = 00H
and count = 00H to a servo will reboot a servo.
Ex）Reboot the ID1 servo.
Hdr ID Flg Adr Len Cnt Sum
Setting both Bit6 and Bit5 to “1” makes it possible to write Flash ROM and reboot the
servo consecutively.
Ex）Write into the Flash ROM of the ID1 servo and reboot the servo.
Hdr ID Flg Adr Len Cnt Sum
Bit4：Initialize the contents of memory map No.4 ~ No.29
Setting this bit to “1” (10H) and sending a packet of address=FFH, length = FFH, count =
00H and data=FFH to a servo will initialize the memory map from No.4 through No.29 to
their initial values.
Please refer to initial values in the “ROM area of Memory Map” (p.18) for more details.
Ex）Initialize the memory map from No.4 through No.29 to their initial values.
Hdr ID Flg Adr Len Cnt Sum
FA AF 01 10 FF FF EE 00
FA AF 01 20 FF 00 DE 00
FA AF 01 60 FF 00 9E 00
FA AF 01 40 FF 00 BE 00
Caution
Caution
If you reset to the factory initial value, the ID becomes 1.

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Bit3 ~ Bit0：Address assignment of a return packet
(1) Data return from predetermined addresses
Setting the Bit3 through Bit0 like the table below when sending a short packet makes it
possible to receive the data of the specified addresses in the servo’s memory map. The Bit0
indicates whether to require a return packet (Bit0=1) or not (Bit0=0). Please refer to the
Table 4.1 Send packet flags (p.11) for setting these bits in sending short packets. The
RS485 half duplex communication, which is used to communicate with servos, does not
allow addressing more than one servo that can send a return packet. After requesting a
return packet, do not send next data until completing reception of the return packet.
Table 4.2 Address assignment of return packet
Bit 3 2 1 0 Function
0 0 0 0 No return packet
0 0 0 1 Return ACK/NACK packet
0 0 1 1 Return the data of the memory map No.00 ~ No.29
0 1 0 1 Return the data of the memory map No.30 ~ No.59
0 1 1 1 Return the data of the memory map No.20 ~ No.29
1 0 0 1 Return the data of the memory map No.42 ~ No.59
1 0 1 1 Return the data of the memory map No.30 ~ No.41
1 1 1 1 Return the specified number of bytes of data starting from the
specified address.
(2) Data return from user-defined addresses
Setting the Bit3 through Bit0 to “1” and sending a short command with the starting ad-
dress whose data you want to receive, the length of data and the count=00H makes it possi-
ble to return the specified number of bytes of the data starting from the specified address.
Available addresses in the memory map are from No.00 to No.139 (00H~8BH).
Ex）Return the data in the memory map addresses from No.42 (2AH) through No.43
(2BH) of the ID1 servo.
Hdr ID Flg Adr Len Cnt Sum
(3) ACK/NAK Packet
If a servo receives a request of sending ACK the Flags being set at Bit0=1, Bit1=0,
Bit2=0 and Bit3=0, the servo send ACK.
The return packet is constituted by only one byte of data like bellow:
Return packet = 07H: “ACK”
FA AF 01 0F 2A 02 26 00

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This notation indicates an address on the memory map. Using this address makes it possible
to write the data of the specified number of bytes determined by the “Length” into the
memory map.
This notation indicates the length of a data block.
Length = the number of bytes of data
This notation indicates the number of servos, which should be set at “1” for a short packet.
This notation indicates the data to be stored in the memory map.
This is the check sum of a packet using 8 bits. Check sum is the value obtained from XOR
operation on all bytes from ID through Data in a packet by a unit of a byte.
If the number of bytes from ID through Data in a packet is two or larger, divide them
byte-by-byte and conduct XOR operation on them.
Ex) Send a command ordering ID1 servo to move to 0 degree.
Hdr ID Flg Adr Len Cnt Dat Sum
The check sum of the transmission data above is as follows:
01H XOR 00H XOR 1EH XOR 02H XOR 01H XOR 00H XOR 00H
●Long Packet
The long packet is used to send the data in the memory map to multiple servos. Please
note, however, that the memory address and the length of the data to be sent are the same
to all the servos.
Packet structure
This notation indicates the front of a packet. Set “FAAFH” for long packets.
“xH” denotes Hexadecimal number.
This should be always kept at 00H.
This should be always kept at 00H.
Address
Length
Count
Data
Sum
FA AF 01 00 1E 02 1C 00 0001
Header ID
Flags
Address
Length Count
Data
Sum
Header
ID
Flags
VID
Data
VID
Data
VID
Number of servos = Count
Len
g
th

15
This indicates an address on the memory map. Using this address makes it possible to write
the data of the specified number of bytes determined by the “Length” into the memory maps of
multiple servos.
This is used to specify the number of bytes of the data for a servo.
Length = the number of bytes of data + 1
This notation indicates the number of servos that data is sent to. VID and data are sent to all of
them.
This field represents the ID of each servo which sends data. Data corresponding to the number of
servos is sent with VID and Data as one set.
This field is the data of one servo which is written to the memory map. Data corresponding to
the number of servos is written with VID and Data as one set.
This field is made up of eight bits which represent the check sum of the packet. The check sum
is the XOR, in byte units, of the set bits from the ID field to the end of the Data field of the
packet string. If there is a packet of 2 bytes or more between the ID and DATA fields, delimit it
into single bytes before XORing.
Hdr ID Flg Adr Len Cnt VID Dat VID Dat VID Dat Sum
The check sum of the send data above is:
00H XOR 00H XOR 1EH XOR 03H XOR 03H XOR 01H XOR 64H XOR 00H XOR 02H XOR 64H
XOR 00H XOR 05H XOR F4H XOR 01H
Address
Length
Count
Data
Sum
FA AF 00 00 1E 03 ED 64 0003
VID
01 64 0002 F4 0105

16
●Return Packet
A return packet is the packet returned from the servo when the Flag field requests a
servo to send a return packet.
Packet structure
This field denotes the beginning of the packet. For a short packet, the header is FDDFH.
This field represents the servo ID.
This field represents the flags which are set in the packet. Each bit shown in the table below
represents a servo state.
Table 4.3 Return packet flags
This field represents the servo memory map address No.
This field represents the length of one data block. The length of one return packet data block
is: Length = Number of return VID + Data bytes
This field represents the number of servos. For a return packet, 1 is always set here.
This field is the check sum. It is the XOR, in byte units, of all the set bits from the ID field to the
end of the data field of a command packet.
Bit Value Function
7 0:Normal, 1:Error Temperature error(Torque off over temperature limit)
6 N/A Reserved
5 0:Normal, 1:Error Temperature alarm
4 N/A Reserved
3 N/A Reserved
2 N/A Reserved
1 0:Normal, 1:Error Received packet error
0 N/A Reserved
Header ID
Flags
Address
Length Count
Data
Sum
ID
Flags
Header
Address
Length
Count
Sum

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Memory Map
●Invariable ROM area
Table 4.4 Invariable ROM area
Area Adress No.
DEC HEX
Initial
value Name Property
00 00H 10H(20H) Model Number L R
01 01H 30H Model Number H R
02 02H 01H Firmware Version R
Invariable
ROM
03 03H 00H Reserved -
( ) For RS302CD
●No.0 / No.1 Model Number(2Bytes, Hex Number, Read Only)
This field represents the model No. (servo model). For the RS301CR, it is:
Model Number L = 10H
Model Number H = 30H
For RS302CD, they are as follows.
Model Number L = 20H
Model Number H = 30H
●No.2 Firmware Version(1Byte, Hex Number, Read Only)
This field represents the servo firmware version. Its value varies depending on the
version at production (0x01 in the example below).
Firmware Version = 01H
※Storing two-byte data to memory map
Two-byte data is stored to the memory map in two individual 8-bit bytes of H (High byte)
and L (Low byte).
Ex.) Issue a 29.2 degrees operation command to servo ID=23.
The command angle is saved to the Target Position item. The commanded value is 29.2
degrees, but since this is 0x0124 in hexadecimal notation, the data actually stored is:
Target Position(L) = 24H
Target Position(H) = 01H

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●Variable ROM area
Table 4.5 Variable ROM area
Area Adress No.
DEC HEX
Initial
value Name Property
04 04H 01H Servo ID RW
05 05H 00H Reverse RW-
06 06H 07H Baud Rate RW
07 07H 00H Return Delay RW
08 08H DCH CW Angle Limit L RW
09 09H 05H CW Angle Limit H RW
10 0AH 24H CCW Angle Limit L RW
11 0BH FAH CCW Angle Limit H RW
12 0CH 00H Reserved -
13 0DH 00H Reserved -
14 0EH
50H(46H) Temp Limit L R
15 0FH 00H Temp Limit H R
16 10H 00H Reserved -
17 11H 00H Reserved -
18 12H 00H Reserved -
19 13H 00H Reserved -
20 14H 00H Reserved -
21 15H 00H Reserved -
22 16H 00H Reserved -
23 17H 00H Reserved -
24 18H 02H CW Compliance Margin
RW
25 19H 02H CCW Compliance Margin
RW
26 1AH
0AH(0FH) CW Compliance Slope RW
27 1BH
0AH(0FH) CCW Compliance Slope RW
28 1CH
B4H(C8H) Punch L RW
ROM
29 1DH 00H Punch H RW
( ) For RS302CD

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●No.4 Servo ID(1Byte, Hex Number, Read/Write)
This data represents the servo ID. Its initial value is 01H.
The setting range is 1 ~ 127 (01H ~ 7FH).
Ex) Rewrite servo ID1 to ID5.
Hdr ID Flg Adr Len Cnt Dat Sum
The relevant servo begins to operate under the new ID as soon as the ID rewrite
command is received.
Note that after the ID was rewritten, if it was not written to the flash ROM, when the
power is turned off, it will return to the previous ID.
●No.５ Servo Reverse（１ Byte,Hex Number,Read/Write）
This shows rotation directions of the servo. The initial value of 00H means the normal
rotation and 01H means the reverse rotation.
If the servo is set with 01H, the limited range of rotation angles is also reversed.
●No.6 Baud Rate(1Byte, Hex Number, Read/Write)
This data represents the communication speed.
The value assigned to each baud rate is shown below.
Table 4.6 Baud rate
Va
lu
e
B
a
ud
r
a
t
e
Va
lu
e
B
a
ud
r
a
t
e
Va
lu
e
B
a
ud
r
a
t
e
00
H
9,600
b
ps
05
H
57,600
b
ps
0
A
H
4
60,800
b
ps
0
1H
14
,
4
00
b
ps
06
H
76,800
b
ps
0
2H
1
9,
2
00
b
ps
07
H
11
5,
2
00
b
ps
03
H
2
8,800
b
ps
08
H
1
53,600
b
ps
0
4H
38,
4
00
b
ps
09
H
2
30,
4
00
b
ps
（Date Bits : 8 bit,Stop Bit :1 bit,Parity : None,Flow Control : None）
Its initial value is 07H (115,200bps).
※When a value other than the set values listed above was set, the communication speed becomes
115,200bps.
Ex.) Set Baud Rate of servo ID=1 to 38,400bps.
Write Baud Rate=04H. At this time, a command with 1 set in bits 5 and 6 of the Flag
field is sent and writing to ROM and restarting of the servo are executed simultaneously.
Hdr ID Flg Adr Len Cnt Dat Sum
FA AF 01 00 04 01 00 01 05
FA AF 01 60 06 01 63 01 04

20
●No.7 Return Delay（１ Byte,Hex Number,Read/Write）
This indicates the delay time for reply when the return packet is required.
The servo sends the return packet in 100μs after receiving data with the setting of 0.
The parameters of No.7 are in units of 001H = 50μs.
If you want to set the delay time for reply to 1ms, write 18 (12H). （1ms=100μs+18x50μs）
Hdr ID Flg Adr Len Cnt Dat Sum
●No.8~No.11 Angle Limit(2Bytes, Hex Number, Read/Write)
These data specify the CW (clockwise rotation), CCW (counterclockwise rotation), and
maximum operating angle based on 0 degree. Set these bits to match the usage
environment.
The rotation limit angle is the maximum value, which can be initially set (±123
degrees). Never set an angle exceeding this value, because the servo may be damaged.
Even if a command value greater than the rotation limit angle is given, the maximum
operating angle is not exceeded.
The setting range is
CW Angle Limit →0°(0000H) ～+150°(05DCH)
CCW Angle Limit →0°(0000H) ～-150°(FA24H).
Ex. 1) Set the CW angle limit of servo ID=1 to 100.0 degrees.
Since the angle is set in 0.1 degree units, when 100.0 degrees is specified, 1000(03E8H) is
set. CW Angle Limit L = E8H, CW Angle Limit H = 03H
Hdr ID Flg Adr Len Cnt Dat Sum
Ex. 2) Set the CCW set values of servo ID=1 to -100.0 degrees (FC18H).
CCW Angle Limit L = 18H , CCW Angle Limit H = FCH
Hdr ID Flg Adr Len Cnt Dat Sum
●No.14 / No.15 Temperature Limit(2Bytes, Hex Number, Read Only)
If an overload is applied to a servo, the heat generated by the motor, etc. will cause the
internal temperature to rise. If the internal temperature exceeds the temperature set here,
the torque will be disabled so trouble will not occur at the servo and the red LED on the
servo will light. To reset the stopped state, send a No. 36 Torque Enable command.
FA AF 01 60 07 01 74 01 12
FA AF 01 00 08 02 E1 01 E8 03
FA AF 01 00 08 02 EE 01 18 FC