Full-board schematic, Rev V1.2. Click to enlarge.

Blocks

Block	Contents
Core RS485	Isolated transceiver U2, with decoupling on both sides
VISO Voltage Auto-Select	Isolated-side supply auto-sensing, which decides whether the isolated-side output level follows a 3.3 V or 5 V system
RS485 Bus Interface & Protection	Bus protection chain: current-limiting resistors → TVS → gas discharge tube → common-mode choke; includes the 120 Ω termination and the fail-safe bias
Connectors & I/O Protection	Logic-side J1 header and bus-side J3 terminal, plus the input resettable fuse and ESD diodes
Auto-Direction Control & Logic Interface	Schmitt-trigger shaping and automatic RE / DE direction switching

Cross-checks

• Logic-side J1: 2.54 mm header, VIN / RX / TX / GND
• Bus-side J3: 5.08 mm terminal, nets OUT_485+ / Earth / OUT_485- (pin order is in the Pinout)
• PE (Earth) is separate from the logic-side GND / GND1: PE is only for discharge and shielding; the two do not share ground
• J1 / J3 use SMD & THT pads: one board can be either surface-mounted or through-hole mounted
• The 120 Ω termination is provided by R5, connected or disconnected with the J2 jumper

Full parameters are in Specifications; the summary table is on the product page.

Contributors: Yua

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