Sending Float Values from Server with Client

[AiWsChan]

Hi all,

I am new to Github and pyModbusTCP so I hope I post in the right place.

Currently, I am working on sending value with decimal points (float) from Server to Client. Below is my simplified code

def Server():
    print (f"[+]Info: Server is Online! \nIP: {server_ip_address}\nPORT: {server_port}")
    server.start()

    x = 12.25

    x_encode = utils.encode_ieee((x))
    print(f"X_Encoded is {x_encode}")

    server.data_bank.set_holding_registers(0, [x_encode])

def Client():
    print(f"[+]Info: Server Connected! \nIP: {server_ip_address}\nPORT: {server_port}")
    client.open()

    x_reg = client.read_holding_registers(0)
    print(f"X is: {x_reg}")

    x_decode = utils.decode_ieee(x_reg)

    print(f"X_decoded is: {x_decode}")

Results: X_Encoded is 1102682522 X is [39322] struct.error: required argument is not an integer (This is for line x_decode = utils.decode_ieee(x_reg))

The question is why when the encoded value (1102682522) goes into register, it changed to another value(39322), what does this means?

Next, since the value is 39322 should be an integer, why does the struct.error message pop up?

Thank you!

`

[sourceperl]

Hi,

Modbus uses 16-bit words, not 32-bit elements.

So, try this :

from pyModbusTCP import utils
from pyModbusTCP.server import ModbusServer
from pyModbusTCP.client import ModbusClient

# init
server = ModbusServer(no_block=True)
server.start()
client = ModbusClient()
client.open()

# write float to server
srv_float = 12.25
srv_f_32b = utils.encode_ieee(srv_float)
srv_f_32b_msb, srv_f_32b_lsb = utils.long_list_to_word([srv_f_32b])
server.data_bank.set_holding_registers(0, [srv_f_32b_msb, srv_f_32b_lsb])

# read float with client
cli_f_32b_msb, cli_f_32b_lsb = client.read_holding_registers(0, 2)
cli_raw_32b = utils.word_list_to_long([cli_f_32b_msb, cli_f_32b_lsb])[0]
cli_float = utils.decode_ieee(cli_raw_32b)
print(f'{cli_float=}')

[AiWsChan]

Hi,

Thank you, thank you so much sir, it works!!

On Fri, 14 Apr 2023 at 7:54 PM, l.lefebvre @.***> wrote:

Hi,

Modbus uses 16-bit words, not 32-bit elements.

So, try this :

from pyModbusTCP import utilsfrom pyModbusTCP.server import ModbusServerfrom pyModbusTCP.client import ModbusClient

initserver = ModbusServer(no_block=True)server.start()client = ModbusClient()client.open()

write float to serversrv_float = 12.25srv_f_32b = utils.encode_ieee(srv_float)srv_f_32b_msb, srv_f32b_lsb = utils.long_list_to_word([srv_f_32b])server.data_bank.set_holding_registers(0, [srv_f_32b_msb, srv_f32b_lsb])

read float with clientcli_f_32b_msb, cli_f32b_lsb = client.read_holding_registers(0, 2)cli_raw_32b = utils.word_list_to_long([cli_f_32b_msb, cli_f32b_lsb])[0]cli_float = utils.decode_ieee(cli_raw_32b)print(f'{cli_float=}')

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