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JXCT · RS-485 sensor
Weihai JXCT Electronics
JXCT standalone soil pH probe (pH scale 0.01).
The JXBS-3001-PH-RS is a single-parameter RS-485 soil probe reporting pH over Modbus-RTU on RS-485 at 9600 bps, 8N1, on DC 12–24 V. This guide documents 4 registers, default Modbus address 1. It does not report moisture, temperature, EC and others. For those on the same bus: moisture → JXBS-3001-TR (4-in-1); temperature → JXBS-3001-TR (4-in-1). Sankhya firmware profile: JXCT_pH_only.
Sankhya Farms supports the standalone JXBS-3001-PH-RS through the JXCT_pH_only profile. It polls at 9600 baud, selects the documented high-precision pH word and applies the JXCT 0.01 scale before the value reaches the free cloud dashboard. This avoids two common integrations that appear to work but are wrong: reading the lower-precision address by default, or decoding JXCT pH with the ZTS family's 0.1 multiplier.
The probe can serve as a simple observation instrument in an orchard, greenhouse, nursery, raised bed, home garden, landscape soil or container trial. A pH history is especially helpful when an amendment or a change in irrigation water is expected to act slowly. The system need not control anything; it can preserve a read-only record for later comparison. For hydroponic nutrient solutions, use an electrode assembly explicitly rated for liquid service rather than assuming that every RS-485 pH probe can remain submerged.
For the primary measurement, read holding register 000DH and multiply the unsigned word by 0.01 pH. The model also exposes 0006H, described here as the lower-precision pH value. Configuration uses 0100H for the slave address and 0101H for baud. A raw value of 642 at the high-precision address is pH 6.42. Sankhya stores 6.42, not the integer 642.
Specs sourced from: Official JXBS-3001-TR datasheet (R208894) and JXCT manuals.
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 |
|---|---|---|---|---|---|---|---|
| 0006H | 40007 | Low-precision pH | uint16 | 0.01 | pH | RO | Scale 0.01. Range 3-9 pH. Accuracy ±0.3 pH. Response time ≤15s. |
| 000DH | 40014 | High-precision pH | uint16 | 0.01 | pH | RO | Scale 0.01. Higher precision variant of pH reading. Use this register for primary measurement. |
| 0100H | 40257 | Device address | uint16 | 1 | — | RW | Range 0-252. Factory default 1. |
| 0101H | 40258 | Baud rate | uint16 | 1 | — | RW | Factory default 9600 bps. 2400=2400; 4800=4800; 9600=9600 |
This probe is configured over the same RS-485 bus using Modbus write commands (function code 0x06). Configure one device at a time on the bus.
Confirmed from official JXCT PDF (v2.0, 2020-10-24). Default baud 9600 (not 4800). Power 12-24V (not 5-24V). Long-term stability ≤5%/year. Two pH registers — use 000DH (high precision) as primary. JXCT config register layout (0100H/0101H) confirmed.
How the JXBS-3001-PH-RS 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 |
|---|---|---|---|---|
| JXBS-3001-TR (4-in-1) | Sibling | Moisture, Temperature, EC, pH | 9600 | Adds moisture, temperature and EC. |
| JXBS-3001-TR (7-in-1) | Sibling | Moisture, Temperature, EC, pH, N-P-K | 9600 | Adds moisture, temperature, EC and N-P-K. |
| JXBS-3001-NPK-RS | Sibling | N-P-K | 9600 | Adds N-P-K, drops pH. |
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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