JXBS-3001-TR (4-in-1)

A JXCT dashboard profile that respects its unusual register layout

The JXBS-3001-TR 4-in-1 cannot safely be decoded by borrowing a ZTS example. Sankhya Farms uses the dedicated JXCT_4in1 profile at 9600 baud: pH, moisture, signed temperature and EC come from scattered addresses, and pH uses a 0.01 scale rather than the 0.1 scale common in the ZTS family. The open-source node applies those rules before sending the four values to the free cloud dashboard.

Once decoded correctly, the probe can provide a useful root-zone record in an orchard, greenhouse, nursery, vegetable plot, home garden, landscape bed or substrate container. It is particularly convenient when someone wants to look up whether watering altered both moisture and EC, or whether pH remained stable during the same interval. Sankhya can be used solely as a remote observer and historical logger; connecting the sensor does not imply automatic dosing. In hydroponics, this buried sensor is most appropriate for compatible solid media. A reservoir needs liquid-rated instrumentation even if it also communicates over 12 V RS-485.

Where do I find pH, moisture, temperature and EC?

Use function code 0x03. pH is at 0006H ×0.01, moisture at 0012H ×0.1%, signed temperature at 0013H ×0.1 °C, and EC at 0015H in µS/cm. Device address and baud are configured at 0100H and 0101H. A raw pH word of 635 therefore means pH 6.35, not 63.5. Sankhya performs the model-specific lookup so charts receive the correct scale.

Why does a generic ZTS decoder give implausible values?

JXCT uses different addresses, a different factory baud and a different pH scale. A response can pass its CRC and still be semantically wrong if decoded with the wrong family profile.

Does the 4-in-1 report N-P-K?

No. The N-P-K addresses belong to the 7-in-1 variant and are absent from this model's documented hardware.

Bus & electrical specs

Specs sourced from: Official JXBS-3001-TR datasheet (R208894) and JXCT manuals.

Modbus-RTU register map

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.

How far to trust this probe's pH

In our orchard, a pH stuck near 7 turned out to be a dead electrode. Until a probe passes the test below, treat its pH as low confidence. Its moisture and EC can still be useful.

Test a JXBS-3001 pH probe

You need: neat white vinegar (pH about 2.4–3.4), borax at about one level teaspoon per litre of water (pH about 9.2), clean water for rinsing, two cups at least 10 cm deep, and a pen pH meter to check each liquid.

1. Keep both cups in the shade. In direct sun a cup reached 52 °C, and the readings jumped.
2. Power the probe for 5 minutes before the first reading. The manual gives no warm-up time, so we use the same wait as our field firmware.
3. Put the probe in the neat vinegar. Check the cup with the pen, then wait until the reading stops moving, about an hour. Note the value.
4. Rinse the probe in clean water. Put it in the borax, check the cup with the pen, wait until it settles, and note the value.
5. Read the result from the later reading in each cup, because the first can still be settling. A working probe reads close to 3 in the vinegar and close to 9 in the borax, so a swing of at least 4 pH is a pass. A dead probe stays between about 5.6 and 7.8, or at exactly 7.00 in both cups.
6. Don't use diluted vinegar. In hard water, a splash can sit anywhere from pH 4 to 7.

A pass means the electrode responds. Its pH is still low confidence until you check it against your pen readings with a two-point calibration. A fail means the electrode is dead: replace the probe, and don't use its pH in the meantime.

Changing address & baud rate

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.

• Set the Modbus slave address by writing register 0100H (PLC 40257) with function code 0x06. DIFFERENT from ZTS family — address register is at 0x0100, not 0x07D0.
• Set the baud rate by writing register 0101H (PLC 40258). Values: 2400=2400, 4800=4800, 9600=9600. DIFFERENT from ZTS family — baud register at 0x0101, not 0x07D1. Factory default 9600.
• Power-cycle the probe after a configuration write for the change to take effect.

Notes & caveats

Upgraded to 0.95 — official JXBS-3001-TR Ver1.1 manual uploaded (R208894, Weihai JXCT Electronics). The 4:1 variant is a subset of the 7:1: same register addresses confirmed — 0006H=pH(×0.01), 0012H=moisture(×0.1%RH), 0013H=temperature(×0.1°C), 0015H=EC(1us/cm), config at 0100H/0101H. NPK registers (001EH-0020H) simply absent on 4:1 hardware. Default baud 9600 confirmed. Power 12-24V DC confirmed. JXCT register layout remains fundamentally different from ZTS/SN family — pH scale 0.01 vs ZTS 0.1, moisture at 0012H not 0000H, config at 0100H not 07D0H.

Common questions

Can I trust this probe's pH readings?

Not yet, from our field tests. A pH stuck near 7 can mean a dead electrode, and a 7.00 means no reading. Test the probe in neat vinegar and borax (see Field test) before relying on its pH.

What baud rate does the JXBS-3001-TR (4-in-1) use by default?

9600 bps, 8N1. It is a Modbus-RTU slave; default address 1.

What supply voltage does the JXBS-3001-TR (4-in-1) need?

DC 12–24 V (≤ 0.15 W (12 V DC)).

How do I change the JXBS-3001-TR (4-in-1) Modbus address?

Write the device-address register with function code 0x06, one device on the bus at a time, then power-cycle. See the Configuration section above.

Is the JXBS-3001-TR (4-in-1) 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.

What does the JXBS-3001-TR (4-in-1) not measure?

The JXBS-3001-TR (4-in-1) reports moisture, temperature, EC and pH only — it does not report N-P-K, salinity and TDS. On the same RS-485 bus, add N-P-K: JXBS-3001-TR (7-in-1); salinity: DFRobot SEN0603; TDS: DFRobot SEN0603.

How many Modbus registers does the JXBS-3001-TR (4-in-1) expose?

This guide documents 6 registers, read with function code 0x03 and written with 0x06 where the register is RW. Documented entries include pH, Soil moisture, Soil temperature, Electrical conductivity, Device address and Baud rate.

How this differs from similar models

How the JXBS-3001-TR (4-in-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.

Related JXCT sensors