DEV_SOIL_7IN1 — 7-in-1 RS485 soil sensor

Reads a 7-in-1 soil probe on Modbus RTU: moisture, temperature, conductivity
(EC), pH, nitrogen, phosphorus and potassium.

Pins

	Pin	Type	Default	What to wire
in-out	`Node`	MODBUS_NODE		The RS485 line's node, as a client
in-out	`Data`	DEV_SOIL_DATA		Settings and status (below)
in	`Enable`	BOOL	TRUE	Read the sensor
out	`Good`	BOOL		Answering, every value plausible
out	`Moisture`	REAL		% (as the sensor reports it)
out	`Temperature`	REAL		°C, negative below zero
out	`Ec`	REAL		µS/cm
out	`Ph`	REAL		pH
out	`Nitrogen`	REAL		mg/kg
out	`Phosphorus`	REAL		mg/kg
out	`Potassium`	REAL		mg/kg

`Data` (DEV_SOIL_DATA)

Field	Type	Default	Meaning
`unit`	USINT	1	The sensor's Modbus address, 1..247 (factory 1)
`map`	DEV_SOIL_MAP	`DEV_SOIL_JXCT`	Its register map (below)
`every`	TIME	T#10s	Read it this often (at least 1 s)
`status`	DEV_STATUS		Status code (see the README)
`statusText`	STRING(30)		Status in words
`age`	TIME		Time since the last good reading

Wiring and line settings

RS485 A/B to the line; the probe's supply as its label says (usually 5–30 V DC).
The common sensor: 9600 baud, 8N1 (SERIAL_PARITY := MODBUS_PARITY_NONE_8N1),
factory address 1. Several probes share one line at different addresses.

Register maps (`Data.map`)

Makers differ, so the map is a setting.

Map	Registers (holding, FC03)	Scaling
`DEV_SOIL_JXCT` (default) — JXCT JXBS-3001 and most generic units	pH 0x0006; moisture 0x0012, temperature 0x0013; EC 0x0015; N P K 0x001E–0x0020	pH ÷100, moisture and temperature ÷10
`DEV_SOIL_LINEAR`	moisture, temperature, EC, pH, N, P, K at 0x0000–0x0006	pH ÷10, moisture and temperature ÷10

Check the map against your sensor's sheet before installing. A wrong map
never shows plausible numbers: the sensor refuses the addresses (No reply) or
the values are impossible (Bad data).

How it works

Plausible: moisture 0–100 %, temperature −40–80 °C, pH 0–14, EC 0–20000 µS/cm,
N P K 0–2000 mg/kg. Anything outside is Bad data and Good drops.
The outputs hold the last good reading while Good is FALSE; Data.age says how old it is.
A sensor that stops answering backs off (up to 16 × every) before it is asked
again, so after a cable is fixed it can take that long to show OK.
Power cut: nothing is kept; the outputs are 0 until the first good reading.

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