CODEWITHSUNDEEP
pythonsocketsserverraspberry-piclient
Anthony
Anthony

Reputation: 65

Sending data back and forth from two Raspberry Pi's with socket library

I've been having trouble sending data between two pi's using socket.send and socket.recv commands in python. I've followed an example on YouTube to help get the code started but whenever I try to send other types of data from the server to the client, the server stops and the client receives an empty value.

Server:

import socket
import time

host = '192.168.10.100'
port = 9988

def setupServer():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    print("Socket created.")
    try:
        s.bind((host, port))
    except socket.error as msg:
        print(msg)
    print("Socket bind complete.")
    return s

def setupConnection():
    s.listen(1) # Allows one connection at a time.
    conn, address = s.accept()
    print("Connected to: " + address[0] + ":" + str(address[1]))
    return conn

def dataTransfer(conn):
    while True:
        data = conn.recv(1024) # receive the data
        data = data.decode('utf-8')
        if data == 'kill':
            print("Server is shutting down.")
            s.close()
            break
        elif data == 'test':
            reply = 1
        else:
            reply = 'Unknown Command'
        conn.sendall(reply)
    conn.close()

s = setupServer()

while True:
    try:
        conn = setupConnection()
        dataTransfer(conn)
    except:
        break

Client:

import socket
from time import sleep

host = '192.168.10.100'
port = 9988

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))

while True:
    command = input("Enter command: ")
    if command == 'KILL':
        s.send(str.encode(command))
        break
    s.send(str.encode(command))
    reply = s.recv(1024)
    print(reply)

s.close()

When I run the 'kill' command it works normally:

server side

client side

But when I try to run 'test', the server script seems to close and the client seems to receive an empty value instead of 1.

server side test

client side test

After looking around it looks like I may be running into blocking/non-blocking issues or the socket.send/socket.recv commands aren't transferring the correct types of data. Perhaps I might have some other errors?

Upvotes: 2

Views: 3830

Answers (1)

Chris Kenyon
Chris Kenyon

Reputation: 218

When the data=="test" condition is hit, you're assigning your reply to an integer value. socket.sendall takes a string argument. Try "1".

As a suggestion, this would be a good opportunity to use pdb to debug if you're not familiar with it. Simply import pdb and wherever you want the program to pause (e.g. in the server's if block where data=="test"), then simply have a statement pdb.set_trace() and it will open an interactive terminal if the message is being received properly.

Upvotes: 1

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