You first need to install the corresponding library files for your Arduino. ModbusMaster.h

Thank you for your reply, Chris. Anticipate update if there are any new developments. If it's an issue with my settings, please let me know as well. Thank you very much.

Thank you for your prompt reply. Yes, I am using version 5.1. I have also tried versions 4.3.1, 4.4, and 5.0, but the issue remains the same. Moving Tx and Tz gradually causes J5 to shift toward the limit switch, and J1 and J4 also slowly deviate from the zero point (though not as much as J5). The upper computer is set to open-loop mode. In the images below: * Image 1 shows the robotic arm in the home position. * Image 2 shows the state after a complete cycle of moving Tx up and down by about 20 cm. After executing the home command, it can still return to the correct "7" shape position.