You can insert the BPI-R4 NIC into CN12 and CN14 at the bottom of BPI-R4-Main, and then fix it with two M2 screws. The BPI-R4-NIC module requires 12V power, so the power on the BPI-R4-Main must be turned on before powering on (SW4 turns to the "on" position, and the 12V LED will light up when powering on).
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