HuiChuan err21 alarm is usually caused by the motor has been damaged or the controller malfunction, you need to contact a professional to check and repair, it is recommended that you do not repair your own to avoid secondary damage.
HuiChuan ERR is a product developed by Huichuan Technology Co., Ltd, which is a company specializing in servo motors and motion control, and its products are widely used in CNC machine tools, automation equipment, packaging machinery, printing machinery, textile machinery, medical equipment and other fields.