Integrated example (Tcp/Client)

Assume that server IP = 192.168.137,200 and open port =20002

and that the received packets are sent to the client as they are (mirroring).

Example 1 : Example of a default TCP client

Python

# Assume server IP = 192.168.137,200 and open port =20002. 
g_sock = client_socket_open("192.168.137.200", 20002)
 
tp_popup("connect O.K!",DR_PM_MESSAGE)
while 1: 
 client_socket_write(g_sock, b"abcd") # The string "abcd" is sent in a byte type.
 wait(0.1)   
 res, rx_data = client_socket_read(g_sock) # Waits for the data from the server.
 tp_popup("res={0}, rx_data ={1}".format(res, rx_data), DR_PM_MESSAGE) 
 wait(0.1)

The example connects to the server and sends the string "abcd". (b converts the string to a byte type.)

The message received from the server is output to the TP.

res = 4 and rx_data=b"abcd" since the server transmits the received data as is.

Example 2 : Examples of a packet transfer

Transmission packet: “MEAS_START" +data1[4byte]+data2[4byte]

data1: Conversion of the integer to 4 byte. ex) 1 → 00000001
data2: Conversion of the integer to 4 byte. ex) 2 → 00000002

ex) data1=1 and data2=2: “MEAS_START"+00000001+00000002

Actual packet: 4D4541535F53544152540000000100000002
Received packet: res=18, rx_data=“MEAS_START"+00000001+00000002
- rxd1 extraction: Conversion of 10th - 14th bytes to an integer
- rxd2 extraction: Conversion of 14th - 18th bytes to an integer

Python

g_sock = client_socket_open("192.168.137.100", 20002)
tp_popup("connect O.K!",DR_PM_MESSAGE)
 
send_data = b"MEAS_START"
data1 =1
data2 =2 
send_data += (data1).to_bytes(4, byteorder='big') 
send_data += (data2).to_bytes(4, byteorder='big') 
  
client_socket_write(g_sock, send_data) 
 
wait(0.1)   

res, rx_data = client_socket_read(g_sock)
tp_popup("res={0}, rx_data ={1}".format(res, rx_data), DR_PM_MESSAGE) 

rxd1 = int.from_bytes(rx_data[10:10+4], byteorder='big', signed=True)
rxd2 = int.from_bytes(rx_data[14:14+4], byteorder='big', signed=True)
 
tp_popup("res={0}, rxd1={1}, rxd2={2}".format(res, rxd1, rxd2), DR_PM_MESSAGE) 
 
client_socket_close(g_sock)

The example connects to the server and sends a byte type send_data.

res = 18 and rx_data=send_data since the server transmits the received data as is.

rxd1 extraction: Conversion of 10th - 14th bytes to an integer
rxd2 extraction: Conversion of 14th - 18th bytes to an integer

The final result is res=18, rxd1=1, and rxd2=2.

Example 3 : Reconnection

Python

def fn_reconnect():
 global g_sock
 client_socket_close(g_sock)
 g_sock = client_socket_open("192.168.137.200", 20002)
 return   
 
g_sock = client_socket_open("192.168.137.200", 20002)
tp_popup("connect O.K!",DR_PM_MESSAGE)
 
client_socket_write(g_sock, b"abcd") 
wait(0.1)   
 
while 1:   
 res, rx_data = client_socket_read(g_sock)
 if res < 0:
     fn_reconnect()
 else:     
     tp_popup("res={0}, rx_data ={1}".format(res, rx_data), DR_PM_MESSAGE) 
 wait(0.1)

The example checks the return value of the client_socket_read() command.

A negative value is returned if the connection to the server is terminated or there is a communication problem.

The function reconnect() is called to attempt a reconnection if a negative value is returned.

Note that the opened socket is closed when a reconnection is attempted.