TCP_RECV failing with Error Code: -34024

dhindhimathai · June 13, 2023 at 3:03 PM

Dear all,

Once again, another difficult problem to solve...

I'm trying to communicate over TCP/IP with the robot. Currently, I'm using a Windows PC with KROSET (Robot-Side) and an Ubuntu Linux PC from which I am starting a TCP/IP client.

On the Robot-Side, I am using the following function found in the Kawasaki TCP/IP manual to recieve a string data.

Code

.PROGRAM recv (.length) ; Recieves data of .length
  .num = 0
  TCP_RECV rret, sock_id, $recv_buf[0], .num, tout_rec, .length
  IF rret < 0 THEN
    PRINT "**ERROR: Something went wrong recieving the message.**"
    PRINT "Error Code: ", rret
    $recv_buf[0] = "000"
  ELSE
    IF .num > 0 THEN
      PRINT $recv_buf[0]
      $recieved_msg = $recv_buf[0]
    ELSE
      $recv_buf[0] = "000"
    END
  END
.END

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I am using this function twice and subsequently to recieve two messages: a header and a command. Let's say that the header has 19 characters and the command has 85. So, I am doing the following in my communication program:

Code

.PROGRAM Communication ()
    WHILE client_connected DO
        ; Receive the header data (19 bytes)
        CALL recv(19)
    
        ; Do something...

        ; Recieve the command data (85 bytes)
        CALL recv(85)
        
        ; Wait for some time
        TWAIT 0.01
    END
.END

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From the client side, I have a python script sending the data all together, hence the header and command are sent in a single string.

On the second CALL recv, I am receiving the error **ERROR: Something went wrong recieving the message.** because in recv() the TCP_RECV returns rret < 0.

The error code in rret = -34024. What is this error all about?

I tried to cross-check the string that I am sending and other possible bugs on the client side... With just one recv() in the Communication program, I don't get any error!

Please help me guys. Thanks in advance.

ShAdOwDrAgOnS · June 14, 2023 at 4:06 AM

Hi,

E4024 is a connection time out.

Typically in industry, robots are setup as client side since you can have multiple robots communicating to a single device which is commonly setup as server side. The basic communication structure is outlined in the picture below for robot as client side. Your code doesn't appear to have used the TCP_CONNECT command to establish the connection first before trying to send data.

Have a look at the manual 90210-1248DEA-E Series-TCP-IP Communication as this contains examples and goes into detail how to use the commands and what the error numbers mean.

**kwakisaki** · June 14, 2023 at 7:21 AM

You also have the question of synchronization and error handling.

So dhindhimathai the timeout error is being produced as ShAdOwDrAgOnS has highlighted.

Therefore it is possible your python script (not knowing your python script) could have already sent the data before the Kawasaki is going to the 2nd CALL, so this is what I would be investigating.

All networks are configured differently regarding whom is client, whom is server, but you need to ensure that you decide which is which and program accordingly.

2 people talking to each other at once, means both people are not hearing what the other is saying.

- Dropped/ignored data packets.

Have you ever had one of those meetings where an object (like a wooden spoon) gets passed around.

No-one can speak unless they are holding the wooden spoon.

So everyone else has to listen.

Pretty basic introduction to any type networking.

Treat your sequence in the similar manner.

TCP_RECV failing with Error Code: -34024

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