Any experience about OpenCM 9.04 with RC100-B for wireless communication

First of all.

Can you ping your DYNAMIXEL?

When I briefly got throguh the basic code (RC-100.ino). It should comm at 1M bps which is different from the default setup of MX-##(2.0) series

Check if your DYNAMIXEL setup is really corresponding to the code in use.

  • To check the connected baudrates, use scan_dynamixel.ino which would return scanning result at specific bps, protocol, ID
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Update 5/5/2022
Success! I have found a solution for a 2XL-430 (ID=11 and 12) hooked up on 485-EXP and powered at 12V, while the OpenCM-904/C is separately powered at 7.4V. I am using a USB Cable (COM4) to download the sketch “RC_485_EXP_Serial_Protocol.ino” listed below from ARDUINO 1.8.16 on the PC (Windows 10). I am also using a USB BT-410 Dongle on the PC (COM24) and on the OpenCM-904/C a BT-410 Receiver connected to its 4-pin UART Port (i.e. Serial2). I also use the Debugging Tool on TASK V.2 to act as a Virtual RC-100 Controller (see screen capture below):

The listing of the sketch “RC_485_EXP_Serial_Protocol.ino” follows (note that it uses only “RC100.h” and “Dynamixel2Arduino.h”:

#include <RC100.h>
#include <Dynamixel2Arduino.h>

#define DXL_SERIAL_3 Serial3 //Serial3 is for DXL Port going to 485-EXP Board
#define DEBUG_SERIAL Serial
const uint8_t DXL_DIR_PIN_3 = 22; //“22” is DIR_PIN for 485-EXP Board
Dynamixel2Arduino dxl_3(DXL_SERIAL_3, DXL_DIR_PIN_3);

RC100 Controller;
uint16_t RcvData = 0;
uint32_t newGoalPosition = 0;
uint8_t id = 0;
uint32_t time_out = 100;

//This namespace is required to use Control table item names
using namespace ControlTableItem;

void setup() {
// put your setup code here, to run once:

int8_t found_dynamixel = 0;
// Use UART port of DYNAMIXEL Shield to debug.
DEBUG_SERIAL.begin(57600); //set debugging port baudrate to 57600 bps
while(!DEBUG_SERIAL); //Wait until the serial port is opened

dxl_3.begin(1000000); // need to match with DXLs baud rate used via Dynamixel Wizard

int8_t protocol = 2;
for(int id = 0; id < DXL_BROADCAST_ID; id++) {
//iterate until all ID in each baudrate is scanned.
if( {
DEBUG_SERIAL.print("ID : “);
DEBUG_SERIAL.print(”, Model Number: ");
if (dxl_3.torqueOff(id))
DEBUG_SERIAL.println(“Error: Torque OFF failed”);
if (dxl_3.setOperatingMode(id, (float) OP_POSITION)) // Position Control mode
DEBUG_SERIAL.println(“Position Control mode OK”);
DEBUG_SERIAL.println(“Error: Position Control mode failed”);
if (dxl_3.torqueOn(id))
DEBUG_SERIAL.println(“Error: Torque ON failed”);

DEBUG_SERIAL.print(“Total “);
DEBUG_SERIAL.println(” DYNAMIXEL(s) found!”);
dxl_3.setGoalPosition(11, 2048); // Init Positions for DXL 11 and 12
dxl_3.setGoalPosition(12, 2048);

void loop() {
// put your main code here, to run repeatedly:
RcvData = 0;
if (Controller.available())
RcvData = Controller.readData();

if(RcvData == (RC100_BTN_U + RC100_BTN_1)) {
id = 11;
newGoalPosition = dxl_3.readControlTableItem(PRESENT_POSITION,id,time_out) + 50;
if (newGoalPosition <= 4095){
dxl_3.setGoalPosition(id, newGoalPosition);
else {
newGoalPosition = 4095;

if(RcvData == (RC100_BTN_D + RC100_BTN_1)) {
id = 11;
newGoalPosition = dxl_3.readControlTableItem(PRESENT_POSITION,id,time_out) - 50;
if (newGoalPosition >= 0){
dxl_3.setGoalPosition(id, newGoalPosition);
else {
newGoalPosition = 0;

I wrote the code as plainly as possible, so that you can adapt it in any way you want to.

Good luck on your project.

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Thanks for your suggestions. I will have a try by this weekend and let you know the results!

Thank you very much for sharing your experience. I will have a try soon based on your shared points and will let you know once I got some results!

Hi, thanks very much for your sharing. It seems I am on the same way and it has been proved correct. My previous code works well with my MX64-AR motors (using Dynamixel2Arduino). And what I did is integrate it with the RC-100 but it failed (communication well but no actuation). I will follow your way to debug my code and will update you as soon as possible!

Hi, thanks for correcting this. I did the corresponding correction but it still didn’t work (correct baud rate, ID, control mode etc). I will follow @roboteer 's sharing to modify my previous code and it would work hopefully.

Hi @roboteer @Yogurt_Man, thanks very much for your kind help and I solved this problem finally!!! :smiling_face_with_three_hearts: Now I can program the master controller and actuate the motors successfully. The main reason of my previous failure is when using the example code I mixed Dynamixel2Arduino and DynamixelSDK library, due to my short knowledge about how to play with RC100 and BT410 modules (I thought they can only work with DynamixelSDK instead of Dynamixel2Arduino). So the connection build but the motor can not understand well the command. :sweat_smile:

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Glad to be of help, and Yes I had found that mixing up libraries confuses and messes me up too, so I am using only “Dynamixel2Arduino” :smile:.