SainSmart Genmitsu 4040-PRO CNC Router User Manual page 28

2. To Determine your Machine's COM port:
· Windows XP: Right click on "My Computer", select "Manage", select "Device Manager".
· Windows 7: Click "Start" → Right click"Computer" → Select "Manage" → Select "Device Manager" from left pane.
· In the tree, expand "Ports (COM & LPT)"
· Your machine will be the USB Serial Port(COMX), where the "X" represents the COM number, for example COM12.
· If there are multiple USB serial ports, right click each one and check the manufacturer, the machine will be "CH340".
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