---
url: /en/docs/xt-c-485-hia-v3_5/getting-started/index.md
---
# Getting Started

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**.

::: warning 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](./pinout.md) — what each pin does and the wiring notes
* [Specifications](./specs.md) — electrical parameters and the two mounting styles
* [Product page](/en/products/xt-c-485-hia-v3_5/) — full parameters, protection chain and component choices

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