When using a USB cable to connect a servo drive to the software, sometimes a strange issue may occur: the software and drive are connected normally at first, but once the servo drive is enabled, the software connection may disconnect intermittently. After the disconnection, reconnecting may also fail.
This is a classic EMI (Electromagnetic Interference) and power supply fluctuation phenomenon in industrial automation commissioning. When the servo drive is enabled, the internal inverter circuit starts high-frequency switching, generating strong electromagnetic harmonics. These can directly disrupt the sensitive USB communication through radiation or cable conduction. This does not necessarily mean that the drive is damaged. For this type of interference, the following solutions can be considered:
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Use a high-quality, interference-resistant USB cable with dual-layer shielding and a ferrite core, preferably a USB 3.0 cable.
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Keep the USB debugging cable at least 20 cm away from the servo UVW power cables and encoder cable, and avoid any direct contact to prevent interference.
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Ground the drive properly: connect the PE terminal of the servo drive, motor housing, control cabinet, and industrial PC housing to the same GND.
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Avoid using multiple USB ports that are located close to each other at the same time. For example, if other USB ports near the USB debugging cable are also in use, disconnect any unnecessary USB devices first to ensure there is no electromagnetic interference between the ports.
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If an immediate solution is needed, you can also use aluminum foil or copper foil to wrap the USB cable and servo UVW power cables.