Hi All,
Maybe someone can shed some light on this. TBT didn't go threw the modbus rtu protocol, maybe thats where the problem lies

Just a case of RTFM?
I have a RS485 sensor, which I hooked to to a USB / RS485 adapter. Seems to work fine, but I don't fully understand how this operates.
I connect the sensor, open an serial program, and data starts to flow. Basically it is pushed every second.
data:
T: 22.2 H: 56.1T: 22.2 H: 56.1T: 22.2 H: 55.3T: 22.2 H: 55.3T: 22.2 H: 54.7T: 22.2 H: 54.7T: 22.2 H: 54.7T: 22.2 H: 54.1
Now this I can easily parse, yet i thought I needed to pull the data out of the sensor? When I try that (pulling), i'm getting some checksum errors.
# Python 3
import minimalmodbus
instr = minimalmodbus.Instrument('/dev/tty.SLAB_USBtoUART', 1, minimalmodbus.MODE_RTU)
instr.serial.baudrate=9600
print(instr.read_register(287, 1))
# response
ValueError: Checksum error in rtu mode: '.3' instead of 'M«' . The response is: 'T: 23.3' (plain response: 'T: 23.3')
I tried changing registers, but it doesn't not seem to matter. I'm guesing the request is sent, yet since the sensor pushes on its own all gets mixed up.
Since it was a cheap sensor from eBay, of course no datasheet. So i'm a bit in the dark how to configure this. Like changing the address (want to use multiple sensors on the bus).
Maybe it's possible to change the mode, but without a proper databasheet it is hard. Or is this all speced in the
modbus rtru protocol?
Anybody that knows whats going on?
Thanks!
Sensor:
https://www.ebay.com/itm/RS485-Temperature-and-Humidity-Transmitter-Sensor-High-Precision-Monitor/123234164113?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649