Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Active TCP connection.

Created by: Impisi at: 8/28/2009 3:53 PM (9 Replies)

Rating (0)

Thanks 2

10 Entries

8/28/2009 3:53 PM	Rate (0)
Impisi Advanced Member Joined: 1/26/2009 Last visit: 3/14/2024 Posts: 22 Rating: (0)	Good day. I do not get communication when I setup a TCP connection between the PLC (CPU 414-2 with CP 443-1 advanced) and an application running on a PC when the PLC is configured to be the active partner (client) . When the PLC is not the active partner (server mode) and the PC's IP address and port are not entered in NETPRO, the PLC & PC application communicate. Also, when a UDP connection is configured in NETPRO, the PLC & PC application communicate. How do I get the PLC & the PC to communicate with the PLC as the active partner (client mode). Equipment used: CPU: 6ES7 414-2XK05-0AB0 CP: 6GK7 443-1GX20-0XE0 Thank you for your assistance.

Suggestion To thank Quote Answer

8/28/2009 4:18 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, I guess the problem is the Winsock. If you open the Winsock and you want to connect to a remote IP and Port you usually do not enter a local port, this way the PC selects a free local port to connect to the remote PLC. If you use UDP there is no connection to be established. So the datagram’s will always be transmitted, if the remote partner is there or not. As I do not know which program you use, have you ever tried to use HyperTerminal instead? Here you should be able to set the program to wait... but you better try by yourself. Maybe it will help. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
Suggestion To thank Quote Answer

8/28/2009 4:23 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	When you setup an active connection on the PLC, you will need to specify the destination port and IP address. I assume that you have set the connection up as a TCP connection to an unspecified partner? One the connection is setup, the on-line connection status should be shown as "active connection establishment in progress". To check this, in NetPRO select the CPU in the SIMATIC station and then click on "Activate/Deactivate connection status" button (shown as a small plug and socket with an 'i' on it). If it does not say this (e.g. "Not available") then you have done something wrong in your NetPRO setup. You will now need a TCP server application on the PC support the connection. Start the PC server application with the port setting set the same value you used as the destination port in NetPRO, and the connection should be established.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
Suggestion To thank Quote Answer

8/28/2009 4:47 PM	Rate (0)
Impisi Advanced Member Joined: 1/26/2009 Last visit: 3/14/2024 Posts: 22 Rating: (0)	Thank you for the quick response J_Bell. I have tried it with HyperTerminal and I could only get communication when the PLC is not the active partner. Why should I get hyper terminal to wait and how do I get it to wait?

Suggestion To thank Quote Answer

8/28/2009 4:59 PM	Rate (0)
Impisi Advanced Member Joined: 1/26/2009 Last visit: 3/14/2024 Posts: 22 Rating: (0)	Thank you for you quick response Smiffy. You assumption (TCP connection with unspecified partner) works when the PLC is not the active partner. When configuring the PLC to be the active partner in Netpro, you have to specify the destination IP & port. It is then that when I monitor the connection on Netpro, the connection comes up with a red square block (I do not remember the words) instead of a green arrow.

Suggestion To thank Quote Answer

8/28/2009 5:44 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	When I stated "unspecified partner" I was referring to the destination station. You will have to select this as your remote station if the remote station is not part of your NetPRO configuration (usually the case when you are connecting to non-Siemens equipment). You are correct in stating that you will have to supply the remote port and IP address (I didn't mention this as you stated that you have done it in your earlier post). So the status is showing as a red square, but what is the text to the right of the square showing? You may need to make the 'Connection Status' column wider so that you can see it. HyperTerminal can be used as a TCP client, but I am not if it can be used as a TCP server. Remember with active communications establishment the PLC is is not hosting the connection, the other end will be (PC). The PC will listen for an incomming connection from the PLC on a specified port (e.g. modbus uses port 502, telnet 23 etc.). When it detects the PLC establishing a connection it will then answer and the connection will be live. The PLC will then keep issuing keep alive packets to prevent the connection from dropping out. You could google "TCP server download". There are a number of TCP server applications available for you to try.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users Impisi

8/31/2009 12:28 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Smiffy, I am not sure if we all talk about the same if we talk about Servers. If I understand you right is every passive partner in an TCP Connection a Server... this is strange because if we see it this way each PC, also a Win 3.11 Workstation may be a server... if it receives a TCP SYN by another station. In my opinion is a server a system which provides services to other systems. Just providing a port to be connected to is not a service, at least not in my mind. In my mind a Service would be for example a FTP Server at Port 20 / 21 or a SMTP Server... or a HTTP Server ... or something like this at an well known port. Just allowing another system to connect to my PC is not a service... it is a defined interface I provide to communicate with an expected partner. Well, as I mentioned the HyperTerminal I will try to explain shortly how we get the system to accept connections also. 1. If you open the HyperTerminal you select TCP/IP, as know. As Port you enter you local Port in the configured active connection on the S7 and the remote IP you leave empty. Then you open the Terminal. 2. The HyperTerminal reports to you that no connection could be established but this what we wanted. 3. Now you open the menu "call" and select "wait for call"... that’s it. A view seconds after this you should be connected. In some cases you may have to try to set the CP to Stop and back to Run again, but than it works. I just tried it here and it works like hell... Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users Ates

9/1/2009 11:30 AM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	I see what you mean. I suppose it depends on what you define as a server. My definition would be something that supports a connection from a client (active partner). I suppose others may require something that goes a bit further and can translate and handle the data as well. The official definition is:- Definition: A server is primarily a program that runs on a machine, providing a particular and specific service to other machines connected to the machine on which it is found. I have just tried hyperterminal as you suggested and it does work. I stand corrected. I didn't realise you could use hyperterminal as a "server". So back to phumula's problem. He should follow your steps 1,2 & 3 in your last post to get hyperterminal ready to support the TCP connection. I suggest he uses port 23 (telnet). He should then define a TCP connection to and unspecfied partner on port 23 with IP address of the PC, and with the "active connection establisment" check box checked. His connection should then open. He says that he is getting the red square. We need to know what the connection status text is to help diagnose his problem. Do you agree?
	Last edited by: smiffy at: 9/1/2009 11:31 AM Last edited by: smiffy at: 9/1/2009 11:30 AM Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
Suggestion To thank Quote Answer

9/1/2009 12:53 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Smiffy, I completely agree with you. I also look forward what results he gets there. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
Suggestion To thank Quote Answer

9/4/2009 5:10 PM	Rate (0)
Impisi Advanced Member Joined: 1/26/2009 Last visit: 3/14/2024 Posts: 22 Rating: (0)	To J_Bell & Smiffy. Good news gentlemen, I have nailed it. I encounted the following problems before getting it right: The company PC blocks applications (i.e HyperTerminal) from lestining to incoming TCP/IP calls and does not provide the option of unblocking. I therefore had to use my personal PC. HyperTerminal kept waiting for the call & a connection was not established. I think the problem was that you can not specify the local port on HypterTerminal. I downloaded a serial port redirector software called "TCP-Com" which allowed me to specify both the local & remote port. It also gives the option to set the PC to TCP client mode or TCP server mode, I used server mode. Thank you very much for your assistance. I have attached a picture of the working netpro configuration. I will now be going one step up, TCP connection between two PLCs over routers. Attachment Active TCP connection.pdf (974 Downloads)
	Last edited by: Phumula at: 9/8/2009 8:37 AM
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on