Why Can't the A6 Servo Be Successfully Controlled Using a Python Script to Send 485 Commands?
Python is a widely used tool, favored for its ease of programming and control. Many of our customers have successfully run servo motors by referring to examples provided here:
A6 Servo Motor RS485 Operation Instruction
However, some customers have reported that even when their programming commands are completely correct, the motor fails to run. Yet, after setting these same parameters using software, the driver operates normally.
Clearly, this indicates a communication issue between Python and the drive via RS485. Let's analyze this step by step:
- Physical Layer
Eliminate any factors that could cause wiring errors. Ensure the RS485 to USB converter cable functions correctly (preferably using one with a higher communication rate).
- Data Layer
The interval between write commands sent by Python may be too short, preventing the drive from correctly receiving the commands. This is currently the primary cause. (Verifying this is simple: after Python sends all the commands, use the drive's panel or software to check if the corresponding parameter values have been successfully modified. If you see default values, it confirms the interval was too short.)
Due to the limitations of the MODBUS RS485 protocol, its communication speed is not very high. When using Python to send commands, if all commands are sent in a single burst, the driver can become somewhat "overwhelmed" while receiving them. In simple terms, the drive might receive a new instruction before it has finished executing the previous one, potentially causing a critical command to be missed, as illustrated below:
The motor will only run after all dozens of commands have been completely sent.
Our recommendation is: Add some delay between each command. This will significantly ease the processing burden on the drive and prevent command loss or failure to run.
Updated on: 28/02/2026
Thank you!