Good that you now have the OpenRB-150 which offers more flexible uses.
Let’s try to use the OpenRB-150 as a mini U2D2 that can only go to 1 Mbps max for baud rate. But that is good enough to take care of troubleshooting your AX-12A.
My physical setup is shown below:
![IMG_025725](https://forum.robotis.com/uploads/db4879/original/2X/7/791664db6514eb8413a7dbdc221bfa58ab0a149b.jpeg)
I supplied 12 V to the Terminal Block and the 150’s jumper is set VIN(DXL). My AX-12A happened to be ID=15. My PC sees the 150 as COM11.
I can see that you are using Arduino IDE 2.21. Can you see the “OpenRB-150” example named “usb_to_dynamixel.ino”? If you don’t see it, you may have to read up on this post at the Arduino Forum (Examples missing 2.2.1 - #7 by ptillisch - GIGA R1 - Arduino Forum) or switch back to Arduino IDE 1.8.19. See picture of this sketch below:
![USB2DXL_Arduino2](https://forum.robotis.com/uploads/db4879/original/2X/f/f6b712f2df712f5a7f780e0aa8b517dc9b8ba531.jpeg)
Anyhow, go to Line 30 and change the default argument from 57600 to 1000000 to match with the 1 Mbps baud rate on your AX-12A. You should be able to compile and download this sketch to your OpenRB-150 fine.
Once that done, start Dynamixel Wizard 2 on your PC and go to Options >> Scan and update the appropriate settings for Protocol 1, COM Port, Baud Rates and Range of the DXl IDs.
![OptionsScanDW](https://forum.robotis.com/uploads/db4879/original/2X/e/e686cd7455df017da69d31368356ea908f6ebbe2.jpeg)
Then you can go back out to the Main Menu and choose Scan and you should be able to connect to your AX-12A (like mine as shown below).
![DW2_Connect_AX-12A](https://forum.robotis.com/uploads/db4879/original/2X/e/e70503a3880b9a3b55ccb758e16fe3bc92ad8ef3.jpeg)
Then you can try different parameters to see if the AX-12A is fully operational. Once you confirm this result, we can then go on to the proper usage of the Dynamixel2Arduino Library.
Also, now that you have the OpenRB-150, you can read the free Kindle Sample of my Arduino book at this link:
https://www.amazon.com/Using-ARDUINO-ROBOTIS-Systems-Ngoc-ebook/dp/B0BPXGQ6YX/
My book uses the Dynamixel2Arduino library directly (not Dynamixel Shield), and there are lots of reference materials in the free sample for the XL-320 and XL-330 used with the OpenRB-150, but unfortunately, the materials on AX-12A with the Mobile Manipulator is not included in the free Kindle sample.