Robotis Dynamixel RX-28 Manuale utente
User’s Manual 2007-03-27
R
Dynamixel X-28
Closer to Real,
DYNAMIXEL RX-28
Contents
1. Summary
1-1. Overview and Characteristics of RX-28 Page 2
1-2. Main Specifications Page 3
2. Dynamixel Operation
2-1. Mechanical Assembly Page 4
2-2. Connector Assembly Page 5
2-3. Dynamixel Wiring Page 6
3. Communication Protocol
3-1. Communication Overview Page 9
3-2. Instruction Packet Page 10
3-3. Status Packet Page 10
3-4. Control Table Page 12
4. Instruction Set and Examples
4-1. WRITE_DATA Page 19
4-2. READ_DATA Page 20
4-3. REG WRITE and ACTION Page 21
4-4. PING Page 22
4-5. RESET Page 22
4-6. SYNCWRITE Page 23
5. Example Page 25
Appendix Page 31
1
DYNAMIXEL RX-28
1. Dynamixel RX-28
1-1. Overview and Characteristics of RX-28
Dynamixel RX-28 The Dynamixel series robot actuator is a smart, modular actuator that incorporates a
gear reducer, a precision DC motor and a control circuitry with networking functionality,
all in a single package. Despite its compact size, it can produce high torque and is
made with high quality materials to provide the necessary strength and structural
resilience to withstand large external forces. It also has the ability to detect and act
upon internal conditions such as changes in internal temperature or supply voltage.
The Dynamixel RX-28 has many advantages over similar products.
Precision Control Position and speed can be controlled with a resolution of 1024 steps.
Compliance Driving The degree of compliance can be adjusted and specified in controlling position.
Feedback Feedback for angular position, angular velocity, and load torque are available.
Alarm System The Dynamixel series robot actuator can alert the user when parameters deviate from
user defined ranges (e.g. internal temperature, torque, voltage, etc) and can also handle
the problem automatically (e.g. torque off)
Communication Wiring is easy with daisy chain connection, and it support communication speeds up to
1M BPS.
Distributed Control Position, velocity, compliance, and torque can be set with a single command packet,
thus enabling the main processor to control many Dynamixel units even with very few
resources.
Engineering Plastic The main body of the unit is made with high quality engineering plastic which enables it
to handle high torque loads.
Axis Bearing A bearing is used at the final axis to ensure no efficiency degradation with high external
loads.
Status LED The LED can indicate the error status to the user.
Frames A hinge frame and a side mount frame are supported by option.
2
DYNAMIXEL RX-28
1-2. Main Specifications
RX-28
Weight (g) 72
Gear Reduction Ratio 1/193
Input Voltage (V) at 12V at 16V
Final Max Holding Torque(kgf.cm) 28.3 37.7
Sec/60degree 0.167 0.126
Resolution 0.3°
Operating Angle 300°, Endless Turn
Voltage 12V~16V (Recommended voltage: 14.4V)
Max. Current 1200mA
Operate Temperature -5 ~ +85℃℃
Command Signal Digital Packet
Protocol Type RS485 Asynchronous Serial Communication (8bit,1stop,No Parity)
Link (Physical) RS485 Multi Drop Bus
ID 254 ID (0~253)
Communication Speed 7343bps ~ 1 Mbps
Feedback Position, Temperature, Load, Input Voltage, etc.
Material Full Metal Gear, Engineering Plastic
Motor Maxon RE-MAX
3
DYNAMIXEL RX-28
2. Dynamixel Operation
2-1. Mechanical Assembly
Option Frames
OF-28B OF-28S
RXOF-28H Horn-28T
4
DYNAMIXEL RX-28
Assembly Sample assembly using option frames.
2-2 . Connector Assembly
Assemble the connectors as shown below. Attach the wires to the terminals using the
correct crimping tool. If you do not have access to a crimping tool, solder the terminals to
the wires to ensure that they do not become loose during operation.
5
DYNAMIXEL RX-28
2-3. Dynamixel Wiring
Pin Assignment The connector pin assignments are as the following. The two connectors on the
Dynamixel are connected pin to pin, thus the RX-28 can be operated with only one
connector attached.
( Note : The pin number of connector’s edge cut side is PIN1)
PIN1: GND
PIN2: VDD(12V~21V)
PIN4: D- PIN3: D+
PIN4: D-
PIN3: D+
PIN2: VDD(12V~21V)
PIN1: GND
Wiring Connect the RX-28 actuators pin to pin as shown below. Many RX-28 actuators can be
controlled with a single bus in this manner.
Control Box “CM-2
Main Controller To operate the Dynamixel actuators, the main controller must support RS485 UART. A
proprietary controller can be used, but the use of the Dynamixel controller CM-2 PLUS is
recommended.
6
DYNAMIXEL RX-28
Connection to UART To control the Dynamixel actuators, the main controller needs to convert its UART
signals to the RS485 type. The recommended circuit diagram for this is shown below.\
CCW
VDD
VDD
The power is supplied to the Dynamixel actuator from the main controller through Pin 1
and Pin 2 of the Molex3P connector. (The circuit shown above is presented only to
explain the use of RS485 UART. The CM-2 PLUS controller already has the above
circuitry built in, thus the Dynamixel actuators can be directly connected to it)
The direction of data signals on the TTL level TxD and RxD depends on the
DIRECTION485 level as the following.
• When the DIRECTION485 level is High: the signal TxD is output as D+, D-
• When the DIRECTION485 level is Low: the signal D+, D- is input as RxD
RS485 UART A multi-drop method of connecting multiple Dynamixel actuators to a single node is
possible by using the RS485 UART. Thus a protocol that does not allow multiple
transmissions at the same time should be maintained when controlling the Dynamixel
actuators.
Main
Controller
7
[Multi Drop Link]
DYNAMIXEL RX-28
Caution Please ensure that the pin assignments are correct when connecting the Dynamixel
actuators. Check the current consumption when powering on. The current consumption
of a single Dynamixel actuator unit in standby mode should be no larger than 50mA
Connection Status Verification
When power is applied to the Dynamixel actuator, the LED blinks twice to confirm its
connection.
Inspection If the above operation was not successful, then check the connector pin assignment and
the voltage/current limit of the power supply.
8
DYNAMIXEL RX-28
3. Communication Protocol
3-1. Communication Overview
Packet The main controller communicates with the Dynamixel units by sending and receiving
data packets. There are two types of packets; the “Instruction Packet” (sent from the
main controller to the Dynamixel actuators) and the “Status Packet” (sent from the
Dynamixel actuators to the main controller.)
Communication For the system connection below, if the main controller sends an instruction packet with
the ID set to N, only the Dynamixel unit with this ID value will return its respective status
packet and perform the required instruction.
Unique ID If multiple Dynamixel units have the same ID value, multiple packets sent
simultaneously collide, resulting in communication problems. Thus, it is imperative that
no Dynamixel units share the same ID in a network node.
Protocol The Dynamixel actuators communicate through asynchronous serial communication
with 8 bit, 1 stop bit and no parity.
Instruction Packet
Main
Controlle
r
Status Packet
ID=0 ID=1 ID=N
Main
Controlle
r
Instruction Packet(ID=N)
Status Packet(ID=N)
9
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