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Renke · RS-485 sensor
Shandong Renke Control Technology
Renke single-parameter TDR soil-moisture probe (×100 scale, baud 9600).
The Renke RS-SD-N01-TR-1 is a single-parameter RS-485 soil probe reporting moisture over Modbus-RTU on RS-485 at 9600 bps, 8N1, on DC 4.5–30 V (RS-485 variant). This guide documents 1 register, default Modbus address 1. It does not report temperature, EC, pH and others. For those on the same bus: temperature → Renke RS-WS-N01-TR; EC → Renke RS-ECTHPH-N01-TR-1. Sankhya firmware profile: RENKE_SD_1in1.
The Renke RS-SD-N01-TR-1 is supported by Sankhya's RENKE_SD_1in1 profile. The node polls the moisture word at 9600 baud, uses the model's 0.01 scale, and sends the finished percentage to the free cloud dashboard. This is deliberately separate from the Renke/ZTS two-in-one profile: the data address, scale and configuration method are different even though all of the products are sold as RS-485 soil sensors.
A moisture-only probe is often enough for irrigation observation in an orchard, lawn, raised bed, home garden, greenhouse pot, landscape installation or soil column. Its value comes from repetition: a curve showing wet-up and subsequent drying can be more useful than a large set of unrelated instantaneous parameters. Sankhya can remain a read-only logger or provide the same series to later decision tools. The TDR-style buried probe should not be repurposed as a hydroponic reservoir sensor without explicit manufacturer approval.
Read holding register 0001H. It is an unsigned 16-bit moisture value with a 0.01 scale. The official example raw value 3885 therefore means 38.85%, not 388.5% and not 38.9%. Sankhya applies the hundredth-percent conversion before storing the reading and does not look for a nonexistent temperature word.
Specs sourced from: Official Renke RS-SD-N01-TR Type-485 manual. (Analog SKU variant is 3.3–5.5 V; the RS-485 unit is wide-voltage.)
Function codes 0x03 at 9600 bps, 8N1. Data registers are read with 0x03; configuration registers are written with 0x06. PLC column shows the 4xxxx Modbus holding-register convention.
| Register | PLC | Parameter | Type | Scale | Unit | R/W | Notes |
|---|---|---|---|---|---|---|---|
| 0001H | 40002 | Soil moisture content | uint16 | 0.01 | % | RO | CORRECTION v3: Scale is 0.01 (divide raw value by 100). Range 0-100%. Accuracy ±3% (0-53%), ±5% (53-100%). |
CORRECTIONS v3 from official Renke PDF: (1) Default baud 9600 not 4800. (2) Scale factor confirmed 0.01 — raw 3885 = 38.85%. (3) Register confirmed at 0001H. (4) Moisture only. (5) Config (address/baud) changed via hardware SET mode with shield wire — no Modbus write registers documented for this model. Probe 304 SS (not 316L).
How the Renke RS-SD-N01-TR-1 compares with the other RS-485 models in the Sankhya library. "Drop-in" means the same parameter set and the same register map, read by the same firmware profile.
| Model | Relationship | Measures | Baud | Difference |
|---|---|---|---|---|
| Renke RS-ECTHPH-N01-TR-1 | Sibling | Moisture, Temperature, EC, pH, Salinity, TDS | 4800 | Adds temperature, EC, pH, salinity and TDS. Default baud 4800. |
| Renke RS-WS-N01-TR | Sibling | Moisture, Temperature | 4800 | Adds temperature. Default baud 4800. |
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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