Write Float Values on Modbus Holding Register Address

[Ricdo7]

I know that modbus does not support floating, DINT and 32bits. I know that you can send a float and that it is possible, but that it is a bit tricky (I can see it myself), but in my project I have to send a float and read a float. I looked at the documentation and all kinds of videos and asked chatGPT, but now I'm slowly getting lost and writing nonsense.

I just want to write 7.7 to PLC memory %MW1 (Real) and read from another register 3.3.

I would be very grateful if you could give me a concrete answer, and not just 'read the documentation'.

Please
Thank you

#Proba
def unos():
str_vrijednost=(float(ulazna_velicina.get()))
print(str_vrijednost)
print(type(str_vrijednost))

builder = BinaryPayloadBuilder(byteorder= Endian.Big, wordorder=Endian.Little)
builder.add_32bit_float(str_vrijednost)
dint_pisi = builder.build()

payload_bytes = bytearray(dint_pisi)
payload_int = int.from_bytes(payload_bytes, byteorder='big',signed=True)

client.write_register(4,payload_int,skip_encode=True)

[janiversen]

The payload builder can do exactly what you need, however if you look at dev (as in not yet released) I have added convert_to_register and convert_from_register functions, that makes life very easy for you.

[Ricdo7]

I can't find where you wrote the convert_from_register functions and convert_to_register . I'm new to Github.

[janiversen]

use branch dev instead of whatever version you are using, then it is included.

[Ricdo7]

I'm not sure how could I write the code. If you can give me a little longer explanation or some banal example how this converter should work and write to the registry. I would be very grateful, thank you.
##########################################################################
class DATATYPE(Enum):
"""Data type enum (name and number of bytes), used for convert_* calls."""
BIT = 0
UINT16 = 1
INT16 = 2
UINT32 = 3
INT32 = 4
FLOAT32 = 5
FLOAT64 = 6
##########################################################################

#Proba
def unos():
str_vrijednost=(float(ulazna_velicina.get()))
print(str_vrijednost)
print(type(str_vrijednost))

payload_int=client.convert_to_registers(str_vrijednost,DATATYPE.INT16)

client.write_register(4,payload_int)

[janiversen]

If you want to convert a float then use the appropriate datatype not INT16. set the number of registers in the call, and also set slave=.