Attempting to pass values from GUI to another app with socket

As i state in the title i'm trying to create a 2 seperate applications, one being a GUI/client and the other being a controller/server.

The GUI uses several sliders to take an input from the user and transfers the value to the controller through a socket.

The controller receives the data and transfers it to another peripheral device, through a SPI connection.

The program transfers the first value and then proceeds to crash. The errors i get are these two :
error connection reset by peer and error broken pipe.

The gui code is

def Configure(e):
Command(0, 0, ch0, reg_X, group_0, ch_0, 1)
def dacCommand(bus,dev,dacVar,command,dacGroup,dacChannel,multFac):
Vref = 3
offsetCode = 0x1555
M = 65535
C= 32768
Iout=dacVar.get()
Vout=Iout*multFac
byte1 = command|dacGroup|dacChannel
dacCode=math.ceil(Vout*(2**16)/(4*Vref)+4*offsetCode)
inputCode=math.floor((dacCode-C+(2**15))*(2**16)/(M+1))
d = struct.pack('<H', inputCode)
data= [0, 0, 0 ]
dataCommand = [byte1, d[1], d[0]]
byte1bin=f'{byte1:08b}'
byte2bin=f'{d[1]:08b}'
byte3bin=f'{d[0]:08b}'
dataString=byte1bin+byte2bin+byte3bin
client_socket.send(bytes(dataString,"utf-8"))
if __name__ == "__main__":          
window = Tk()
window.title('DACs board control')
window.geometry('1920x900')
tab_control = ttk.Notebook(        window)
tab2        =         Frame(  tab_control)
tab_control.add(tab2, text= 'dev1 control')
tab_control.pack(expand= 1,  fill= "both")
ch0 = DoubleVar()
ttk.Label(tab2, text= "ch0 (V)", font= ("Calibri", 12)).grid(column= 0, row= 0, padx= 10,     
pady= 5)
ch0Scale = Scale(tab2, from_= 0, to = Vmax, resolution = 0.05, state = "normal", variable= 
ch0, command= Configure, font='Helevetica 11', length = 200, width = 15).grid(row = 1, 
column = 0,  pady = 5, padx = 10, sticky = 'w')
mainloop()

The controller code is :

if __name__ == "__main__":     
spi=spidev.SpiDev()
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((socket.gethostname(), 1234))
s.listen(5)
conn, address = s.accept()
print(f"Connection from {address} has been established.")
while True:
command = conn.recv(24)
if not command:
break
spi.open(0,0)
spi.mode = 0b01
spi.max_speed_hz = 1000000
part1=command[:8]
part2=command[8: 16]
part3=command[16:]
spi.xfer2([int(part1,2),int(part2,2),int(part3,2)])
spi.close()
conn.close()

The client and server are doing a single send and receive operation, to fix your problem you should make the client and server maintain the connection by a continuous communication.

first on the server side you should modify your code like this:

if __name__ == "__main__":
# ...
while True:
conn, address = s.accept()
print(f"Connection from {address} has been established.")
while True:
command = conn.recv(24)
if not command:
break
# ...
conn.close()

then on the client side:

from tkinter import filedialog
def Configure(e):
# ...
if __name__ == "__main__":
# ...
window.createfilehandler(client_socket, tkinter.READABLE, Configure)
# ...
mainloop()
window.deletefilehandler(client_socket)

it should work but you might have more issues because of recv you should look into asynchronous programming or multithreading.

No need to send actual ones and zeros. Send the bytes. It appears you need to send the input code big-endian, so use > instead of < in the format string and include the command byte. Use sendall to ensure all 3 bytes are sent (very likely even with send() but send() can send less under the right conditions.

data = struct.pack('>BH', byte1, inputCode)
client_socket.sendall(data)

On the client, read the 3 bytes. Note you should check the return value of conn.recv to make sure it actually receives 3 bytes. The value is a maximum to receive.

data = conn.recv(3)
if len(data) != 3:
# deal with it
spi.xfer2(list(data)) # list on bytes data will return the values,
# e.g., b'\x01\x02\x03' returns [1, 2, 3].
# May not be needed if the function accepts
# byte strings...