bytesize | Simple byte size formatting library | File Utils library

After all, the answer was quite easy as it has been part of the "product.component.html" page before the table view has been replaced by a list view.

The HTML tr tag featured the following jhiSort directive

Does the library auto-assign the slave number, or we have to define it?

With MinimalModbus you pass the slave ID through in the minimalmodbus.Instrument('/dev/ttyUSB0', 1) call (the 1 is the Slave ID). How you set the slave ID on the device itself varies (this is not covered by the Modbus over serial line spec; could be a configuration program, DIP switches, based on the serial number etc. Other libraries may take different approaches (for example defaulting to Slave ID 1).

From the datasheet, is it the register number is the address?

The header in the spec tables says "No(Address)" so "10001(0000)" means register 1, address 0 (these refer to the same thing; I recommend reading the "Modbus: When 40001 Really Means 1, or 0 Really Means 1" section in this article which explains some of the issues around addressing).

And how many decimals do I expect if there's two data sequence as a response?

Not quite sure what you mean by "two data sequence". The Modbus spec only details the sending of bits (coils) and 16 bit values (input/holding registers). From a quick look at your spec it looks like this device just uses a single registers; for instance "OUT1 Output time" has "unit: ×10㎳" so take whatever is in the register and divide by 10 to get ms.

Is the CRC16 check already included within the library as i shouldn't code it?

Any decent Modbus library will look after the protocol details (such as CRC) for you (so no you don't need to code this; MinimalModbus will calculate it for you)

The device manual isn't clear about the register start address, but the first register it mentions has the address of 1.

Similarly, the mbpoll command-line utility (not the one with GUI) isn't very clear about the start address. But its documentation mentions that the default value for -r parameter is 1.

I think it's safe to assume that both use the same addressing which starts from 1, as the command-line tool has no problems accessing the value.

But MinimalModbus API clearly mentions that its register start address is 0. So when using this library, you need to use registeraddress = 45 for accessing the temperature, not 46 or 40046.

But why won't 46 work? Normally, one would expect it to grab data starting from the next register and print some garbage, but not timeout. But we can't know how the device works internally. Maybe a request to access the temperature register actually triggers some measurement function and then returns a value. A request to access an unaligned data (with a wrong register value) can be simply rejected by the firmware.

If you still get timeouts with registeraddress = 45, your Python runtime may have some problems accessing the serial port. As I stated in my comment, I recommend using a logic analyzer to see what's going on on the wire. Without such a tool, you're doing blind-debugging.

The problem lies with

the output from python is correct. bytes(integer) creates an array of provided size, all initialized to null in your case size = 1, bytes(1), so the output that you have is 0x00 if you try bytes(10) the out put will be b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'.

what you need to do is to change ser.write(bytes(1)) to ser.write(bytes('1',encoding= 'utf-8')) that should work

Skip invalid lines with try/except:

Thanks to @Brits i got it running. I had to use read_float(0, functioncode=4, number_of_registers=2) where 0 is decimal. If i want to read 001A i had to convert from hex to dec = 26. Works very good

Okay, so I figured it out myself with some testing. Here's my answer if someone comes here with the same problem or related.

The problem was that the first line of the rs respond was containing some uneeded values and it was blocking the port from other answers.

Option 1) Modify the library to return the "answer" variable from private function _communicate to your program.

Option 2) Save the debug log output to a variable and filter this variable for the string.