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Thread: Dynamixel XL340-W250-T with only OpenCM9.04

  1. Dynamixel XL340-W250-T with only OpenCM9.04

    I got two Dynamixel XL430-W250-T that I want to use with an OpenCM9.04 C-Type Board. Is it possible to make them work without the OpenCM 485 Expansion Board?

    I made some tests, using breadboard wires to connect a XL340 with a 3 Pin TTL Port on the OpenCM9.04 (normally used for XL320). With the OpenCM IDE and the getModelNumber code example I was then able to read out the model number (displays 1060). However, I can’t make it run, turn on the led or change the ID using the examples, simply nothing happens.

    Furthermore, in the R+ Manager the XL340 can´t be found when I do an “Update & Test”.

    I already thought, that the power via USB cable might be too low, but using a 11 V power supply connected to the OpenCM9.04 also doesn´t help.

    All these tests work fine using a XL320, so there´s no problem with the board. Also, the connection to the XL430 seems to work - at least enough to read out the model number.

    Anyone has an idea what the problem might be? Do I really need to use the Expansion Board?

    Best regards

  2. Re: Dynamixel XL340-W250-T with only OpenCM9.04

    Solved it at least a bit. Made a stupid mistake… Register addresses of XL320 and XL430 are different, so using the pre-defined functions for XL320 doesn’t work with the XL430 – makes sense .

    By addressing the registers manually using the OpenCM IDE I’m now able to change the ID of the XL430 and make its LED blink. But still I can’t make it rotate. I changed the Operating Mode to Position Control Mode and set the Goal Position, is there anything more to do?

    Also, I’m still not able to find the XL430 in the R+ Manager when I do an “Update & Test” but I can make a Firmware Recovery (which did not help).

    Then I tried the Arduino IDE with the Dynamixel Workbench and ran the Monitor example. When I ping the XL430 I get the following error: “[RxPacketError] Hardware error occurred. Check the error at Control Table (Hardware Error Status)!” So, I guess something is wrong but I can’t access the Control Table value to check what the error exactly is...

    Any ideas?

    Best regards

  3. #3

    Re: Dynamixel XL340-W250-T with only OpenCM9.04

    Yes you can control XL430 servos using OpenCM9.04 board without the OpenCM RS485 expansion board.

    I have done it in the past using external power hub, where I hacked up a cable to adapt from XL320 connector to AX servo connector, I did not include the voltage connection here or maybe I did... But then I needed a AX to XL servo wire (robotis sells), and I connected external power to the hub. Later I made a special hub for this, which is like the one Trossen now sells:

    Which you can jumper from OpenCM board to it using XL320 cable and it has XL/XM connnections...

    I need to get back playing again to remember more of which of the Robotis apps works with Protocol 1 versus Protocol 2 servos.
    But I am assuming the one you are trying works with Protocol 2.

    With many of these applications, you have to go through and properly configure them, if they are going to find servos and the like.

    Example: The xl320 servos default to a baud rate of 1000000 where as I believe your servo defaults to 57600, So for it to find your servo, you need to go in and view the OpenCM9.04 object, and set the baud rate to that of your servo, as well as make sure it is looking at the right buss. In your case probably is (1 versus 3)... Then you need to go back out, you may have to change your connection settings for the app, and then do another scan and then hopefully it will find your servo.

    If it can talk to the servo, and want to update the servos ID or baud or any of the control table items. You need to make sure the Torque enable setting is off. The servo will not allow changes to happen when that value is on.
    If you wish to make it move, you need to turn on the torque enable:

  4. Re: Dynamixel XL340-W250-T with only OpenCM9.04

    Hey KurtEck,

    apparently my last post got lost, maybe because I'm new here and my posts have to be checked by a moderator. Hopefully this time it will show up.

    To sum it up: I could get it work. I made two mistakes... I used OpenCM and tried the pre-defined functions that worked with the XL320. Indeed, I did not recognize, that the register addresses of XL430 and XL320 are different, so the functions (except the one to return the model number) couldn't work. Then I switched to the Arduino IDE with the Dynamixel Workbench to make my life easier.

    Further more, I did't connect an appropriate power source. I didn’t expect the XL430 to turn with only the 5V USB cable connected, but because I was able to receive the model number, I thought some of the read/write commands should also work. Well, I was wrong...

    So now, with a 12V power supply connected and using the Arduino IDE with Dynamixel Workbench, everything works fine

    Anyway, thanks for your help!

  5. #5

    Re: Dynamixel XL340-W250-T with only OpenCM9.04

    Glad you got it working.

    I typically have avoided using the Dynamixel Workbench as it adds a reasonable amount of overhead for every call and it might restrict you on what things you can query and set. Luckily not as bad as earlier on, but still...

    For example I hated that every time I do anything like set the goal position, you pass in a string for the parameter name, it then looks up your servo, in its tables, figures out it is in some group of servos, of type X, and then gets a table of strings, which it then does a string compare of the string you passed in, against each of the strings until it finds a match, which gets it a table index with the proper register and size of register... to do that one operation. And while doing this, it did a few malloc/frees for each thing...

    With the SDK, I would typically find the servos, Grab the packet handler and then use the functions like:
    readTxRx or read1TxRx ... to fetch stuff.

    And likewise functions like write1ByteTxRx ...

    Take a look at some of the examples like dxl_monitor.ino for more details

  6. Re: Dynamixel XL340-W250-T with only OpenCM9.04

    Hi I am using following connections:

    PC -->U2D2 --> Dynamixel 430

    And Dynamixel is powered using SMPS2Dynamixel. I can see 12 at Dynamixel terminals. However I am not able to see detect Dynamixel using R+Manager or any Wizard. I tried multiple ways but couldn't able to connect using U2D2. Am I missing someting?

  7. #7

    Re: Dynamixel XL340-W250-T with only OpenCM9.04

    FYI - I don't have a U2D2, So may not be as much help here...

    I assume you are connected up like they show in:

    And if you bring up R+ Manager:

    That you have selected the correct communications port that is associated with the U2D2, which on the main update/test page I believe is near the upper right.

    Now assuming that comes up, and you can see control table associated with the U2D2? If so, is the Baud rate set to match those of your Dynamixels?

  8. Re: Dynamixel XL340-W250-T with only OpenCM9.04

    @KurtEck: Thanks for your advice. Currently it's about to see what i can do with this servo so for now these functions are okay but later it might be necessary to take a look on what you recommended.

    @KKK: Sorry, can't help you with this as I don't have a U2D2. Only thing I can tell, is that I'm also still not able to detect the XL430 in R+ Manager, but everything else works fine.

  9. Re: Dynamixel XL340-W250-T with only OpenCM9.04

    I'm also trying to run an XL430 with the OpenCM9.04 (Type C) but unfortunately without any success.

    I'm using an external power supply (12VDC) wired to the controller board and to the servo motor. I use a common ground and the TTL ouptut directly beneath the +/- sockets on the board. The servo motor is powered up (since the LED is on for about a second).
    (I could do a drawing if needed.)

    For the code I'm using the Dynmixel2Arduino library but neither the example to scan through the baudrates & ids nor any other example is resulting in a connection to the servo motor. (I'm using the status LED on the controller board for feedback.)

    I read something about modifying the configuration of the controller board to be able to communicate bidrectional with the one TTL pin when using the 485 EXP but I did not change anything right now.

    After all I'm insecure whether I just missed some small little thing to get it work. Do you guys have any hints?

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