Hello,
I am trying to establish communication between a S7-300/400 and a PC application (VB?) over open TCP/IP.

I was able to find the FB (TSEND/TRECV) required on the Simatic system but was not able to find an appropriate VB program. Can anyone advice on this. A sample VB program will go a long way!

Thanks in advance

SCORPIO

Hello,

I'm not familiar with VB, but I have succesfully done it with C#. This is not very somplicated. You write program with VB as it would communicate to other PC via TCP. Here is little example from C#. I hope it will help:

.....

Socket client = null;

TcpListener server = null;
const int port = 62000;

IPAddress localAddr = IPAddress.Parse("172.16.0.3");
#endregion

try
{

server = new TcpListener(localAddr, port);

server.Start();

this.SetText("Waiting for a connection... ");

do
{

Byte[] bytes = new Byte[10];

if (server.Pending())
{

client = server.AcceptSocket();

this.SetText("Connected!");
}

else
{

Thread.Sleep(100);
}

if (client!=null)
{
// connection ready here, start reading

The main think is to create client socket and server TCPListener objects. It must be similar to VB. At least to VB.NET
But I strongly recommend of using OPC interfaces. There are lots of examples and you can work with any S7 connection, not only TCP.

Thanks a lot--> Scorpio