基本TCP连接

Question

I am trying to control some test equipment with a TCP connection. The equipment comes with software that you are able to control over TCP. Basically, you can input the IP address and port of the client computer and there is also an indicator light that shows when there is an open listening session on that port (this is all on the equipment software interface)

I have tested this using SocketTest3 (free software) and am able to start a listening session as well as send commands from another computer. Now, I want to control the equipment with Python. I am running the code for the server and client on the same machine as the test equipment (using local IP address). When I simply run the code (with the equipment software closed) I am able to send, receive, and print the messages I send. When I have the equipment software open (necessary for control) I am able to start a listening session (indicator light shows up on equipment software), but nothing happens (no errors and nothing received) when I send commands. The messages are also not sent back to the client to print.

Any ideas? It's probably something very simple that I'm missing.

Server code:

import sys
import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
TCP_IP = '127.0.0.1'
TCP_PORT = 8001
s.bind((TCP_IP, TCP_PORT))
s.listen(5)

connection, client_address = s.accept()
BUFFER_SIZE  = 20
print 'Address: ', client_address

while 1:
    print "receiving..."
    data = connection.recv(BUFFER_SIZE)
    print data
    if not data: break
    print "received data:", data
    connection.send(data) # echo
connection.close()

Client code:

import socket

TCP_IP = '127.0.0.1'
TCP_PORT = 8001 
BUFFER_SIZE = 1024
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TCP_IP, TCP_PORT))

print "sending message..."
s.sendall('ST<CR>') # Send command
print "receiving message..."
data = s.recv(BUFFER_SIZE)
s.close()
print "received data:", data

Answer 1

For those wondering what is missing from camerausb's code, I think he was not seeing anything from the client's print statement because he did not use repr() to format the data. I had a similar problem, but this worked for me:

print 'Received', repr(data)