What baud rate does the XY-MD02 use by default?

9600 bps, 8N1. It is an ASCII device, not Modbus.

Is the XY-MD02 compatible with the Sankhya platform?

Yes — it is in the Sankhya RS-485 sensor library and the firmware-generation pipeline can produce node firmware for it.

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MD02 · RS-485 sensor

Generic OEM — air temperature & humidity

XY-MD02

Name: XY-MD02
Brand: Generic OEM — air temperature & humidity

Air temperature + relative humidity transmitter. ASCII protocol on the bench-tested revision.

✓ Verified for SankhyaAir temp.HumidityVerification 1.00 · byte-verified

Quick reference

Bus & electrical specs

Note. The bench-confirmed revision answers a bare 4-byte ASCII command (READ) at 9600 8N1 — it is NOT a Modbus-RTU slave. It also ships with the factory label upside-down (see Known Issues).

Protocol

RS485 ASCII/common protocol

Default baud

9600 bps

Serial format

8N1

Function codes

—

Supply voltage

DC 5–30 V

Power

< 0.2 W

Default address

N/A — fixed-ID ASCII revision (see notes)

Ingress / housing

Wall / panel housing (not IP68)

Probe / element

SHT-class digital RH/T element behind vented cap

Operating temp.

−40 to +80 °C

Firmware profile

XY_MD02_ASCII_READ

Specs sourced from: XY-MD01/MD02 family datasheet + Sankhya v4 node bench test.

Protocol

This unit speaks ASCII, not Modbus

The revision Sankhya bench-tested is not a Modbus-RTU slave. A full Modbus scan (6 baud rates, 8N1/8E1/8O1, function codes 0x03/0x04, several register starts) returned zero valid responses. Instead it answers a bare four-byte ASCII command with a plain-text string — no CRC, no register map.

# Read air temperature and relative humidity using the tested common protocol. request ASCII "READ" (hex 52 45 41 44) response 16.02C,55.85% # air temperature = 16.02 degrees C; relative humidity = 55.85% RH

Response format <temperature>C,<relative_humidity>%, parsed with ^(-?\d+(?:\.\d+)?)C,(\d+(?:\.\d+)?)%$:

Field	Type	Unit	Capture
air_temperature	float	°C	group 1
relative_humidity	float	%RH	group 2

Line ending matters. The working command is the literal bytes for READ with no terminator — appending CR, LF, or CRLF all return nothing. Because it can share an RS-485 pair with 4800-baud Modbus soil probes, firmware must switch the UART to 9600 8N1 before addressing it.

Known issues

Factory label is upside-down

The printed sticker contradicts the PCB silkscreen

On the XY-MD02 units we received, the adhesive label on the vented cap is rotated 180° relative to the board's own silkscreen. Wire by the sticker as printed and you swap the RS-485 data pair with the power pair — feeding DC into the data lines and the bus signal into the supply pins. Best case the sensor never answers; worst case you damage it.

The PCB silkscreen is the authority. Open the cap once and confirm against the board. Looking at the terminal block with the four screws toward you, the correct order is:

Terminal 1

B−

RS-485 data B (D−)

Terminal 2

A+

RS-485 data A (D+)

Terminal 3

V−

Power ground (GND)

Terminal 4

V+

Power +, DC 5–30 V

Either re-apply the label the right way up (steps below) or ignore the sticker entirely and wire to the silkscreen. The data terminals are marked B− / A+ — pair them to your bus B / A respectively.

The problem · what's wrong

Sankhya XY-MD02 known issue, step 1 — As shipped — **As shipped**The unit arrives with the label printed upside-down. Read as printed, it puts the power pair (− +) where the RS-485 data pair actually sits.

Sankhya XY-MD02 known issue, step 2 — Opened — the ground truth — **Opened — the ground truth**Pop the vented cap off. The PCB silkscreen reads, left to right, B− A+ V− V+. That is the real terminal order — and it is the opposite of the upside-down sticker beside it.

The fix · how to correct it

Sankhya XY-MD02 known issue, step 3 — Re-labelled — **Re-labelled**Peel the sticker and re-apply it the right way up. It now reads the same direction as the silkscreen underneath — B− A+ on the RS-485 pair, − + on power.

Sankhya XY-MD02 known issue, step 4 — Ready to wire — **Ready to wire**Closed and corrected. Whether you trust the new label or the silkscreen, both now agree on the pinout.

Documented from physical units, Sankhya field bench, June 2026. Your unit's revision may differ — always verify against its own silkscreen.

Field notes

Notes & caveats

Directly confirmed on a Sankhya v4 node. The bare four-byte ASCII command READ at 9600 8N1 returned 16.02C,55.85%. This exact revision should use XY_MD02_ASCII_READ, not a Modbus register-map profile. It can coexist with 4800-baud Modbus sensors on the same physical RS485 bus by switching UART baud/protocol between polls.

FAQ

Common questions

What baud rate does the XY-MD02 use by default?: 9600 bps, 8N1. It is an ASCII device, not Modbus.
What supply voltage does the XY-MD02 need?: DC 5–30 V (< 0.2 W).
Is the XY-MD02 compatible with the Sankhya platform?: Yes — it is in the Sankhya RS-485 sensor library and the firmware-generation pipeline can produce node firmware for it.

Run this sensor on a Sankhya node

Every sensor on this page is in our RS-485 library. Pick your model, and the firmware-generation pipeline builds the Modbus (or ASCII) polling code for an ESP32-S3 node — no hand-coding the register math.

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