1. Choose a mounting style: SMD (solder the castellated half-holes flat) or through-hole (insert a 2.54 mm pin header / 5.08 mm terminal). The two are electrically equivalent — pick whichever suits your production line.
2. Check the supply: VIN within 3.0 – 5.5 V, and the logic-side GND common to your MCU.
3. Connect the bus: run A / B to the RS-485 bus as a twisted pair where possible; terminate PE to earth nearby.
4. Set the termination: close the on-board jumper for 120 Ω only at the two physical ends of the bus; leave intermediate nodes open.
5. Power up and use: half-duplex transmit/receive is automatic — TX drives RE / DE directly, so the software never handles direction.

Check before wiring

• PE must be terminated to earth nearby: the gas discharge tube uses PE as its discharge path; with it floating, surge protection is noticeably weaker
• Never short the isolated-side PE to the logic-side GND: once the two share ground, the isolation is gone
• Connect the 120 Ω only at the two physical ends of the bus: keep intermediate nodes open

Next Steps

• Pinout — what each pin does and the wiring notes
• Specifications — electrical parameters and the two mounting styles
• Product page — full parameters, protection chain and component choices

A detailed usage guide with waveforms and oscilloscope captures is to be added.

Contributors: Yua

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