Hi @lamhung81,
The Blue Robotics guide you linked to (2.) is intended for people who’ve bought their DVL A50 through Blue Robotics since we started our The Reef initiative in June, because we sell them with the wiring pre-prepared for plugging directly into our Ethernet Switch. As mentioned in that guide,
I’m not certain what you’re asking here - our tutorial does not mention the I/O Interface board because we sell the DVL with connectors on the wires. If you don’t have those connectors then you won’t be able to follow our tutorial because your hardware won’t match.