Taidacent SHT30 RS485 Modbus RTU Temperature and Humidity Sensor Transmitter for PLC and DCS Room Thermocouple Monitoring

Excellent for price. n = no parity. My PLC only allows 400001 as starting address, where the instructions said 40001. However, when I entered 400001 it did not matter, it gave me the results. Don't forget to divide the numbers by 100 to get the correct temperature and % humidity. Convert from Deg C to Deg F by multiplying by 1.8 and adding 32. I also forgot to hook up the red wire. It works fine with 24 VDC.

Works fine, you just have to poll function code 03 (holding registers) and the transducer I received had slave address 01. Temperature is located at register 1 (address 0) and humidity is register 2 (address 1). IMPORTANT I found that if you poll more than 2 registers in one message, the transducer seems to go into an 'auto broadcast' mode, where it automatically transmitts on a 1-2 second interval. This gave me a bit of a headache.

It connected right up to my USB-to-RS485 interface, and my PC could read it right away using python's pymodbus module. Value agrees with other temperature sensors.

Excellent product. Very accurate. Only reason that I did not give it 5 stars is that I could not set the baud rate. The documentation about baud rates has errors. Address 66 and 67 are referenced as baud rate. The write register example reads the register. If 9600 baud is fast enough, this product works fine.

Had it up and communicating with my laptop in a matter of minutes. It's currently wired up to a Click PLC and giving good results. It gives readings inline with other sensors of the same grade.

Exactly what I needed, I had it working in minutes.

I picked this up to integrate into a small home lab / workshop monitoring setup, and overall I’m pretty impressed with what you get for the price—but you definitely need to know what you’re doing going in. First off, this is very much an industrial-style sensor, not a plug-and-play consumer gadget. It uses RS485 with Modbus RTU, so I wired it into an RS485-to-USB adapter and pulled data into a Raspberry Pi running a simple Modbus polling script. Once configured, it worked reliably and consistently. The default baud rate and address were exactly as documented, and I didn’t run into any weird quirks communicating with it, which was a pleasant surprise. Accuracy seems solid. I tested it against a couple of other sensors (including a calibrated hygrometer), and it was within a few percent for humidity and about 0.5–1°C for temperature, which is totally acceptable for environmental monitoring. The specified humidity accuracy (~±3% RH) seems realistic based on what I observed. Build quality is better than expected. The probe has a metal filter cap and feels like it’s meant for real-world use rather than just a hobby project. I mounted it in a small enclosure to monitor temperature/humidity swings in my garage, and it’s been stable over a few weeks with no drift or dropouts. A couple of downsides: - Documentation is minimal and assumes you already understand Modbus registers and scaling. You’ll need to divide raw values (e.g., by 100) to get real readings, which isn’t explained clearly unless you dig into the manual. - No plug-and-play software—this is strictly DIY integration. - Cable is a bit short, so plan for extensions if you’re installing it somewhere permanent. Where it really shines is reliability once it’s set up. I have it polling every few seconds and logging data, and it hasn’t missed a beat. If you’re tying it into a PLC, Home Assistant (via Modbus), or a custom monitoring system, it’s a great little sensor. Bottom line: If you’re comfortable with RS485/Modbus and want a durable, accurate sensor for automation or monitoring, this is a great value. If you’re expecting something USB or Wi-Fi out of the box, this isn’t it.

Got this working by powering red wire with 24vdc, green ground. Baud rate 9600, 8 data bits, parity none, 1 stop bit, slave node # 1.