I'm having some problems creating a simple connection over TCP/IP. I'm using a CPU315-2 DP/PN with build-in ethernet interface and I'm writing the code in SCL. The ethernet connection is working fine for downloading programs into the system, so the ethernet connection seems ok, so I think the problem is in my code.

The goal is to generate a SCL-program that tests a simple socket connection by opening port 4096 for communications, then I'm supposedto connect to that port using Telnet from a PC and the PLC outputs an infinite stream of 'Hello World' strings, butTelnet says "Unable to connect to 192.168.2.2 port 4096"

I've basically used standard settings of the UDT65, just modifying port number = 4096(can be any port) and interface = 3 (internal). By using the default setting that sets don't care on remote address, I'm assuming it allows any client to connect to my open port.

I've set telnet to "TCP/IP (WinSock)" and my PLC's IP-number=192.168.2.2 and port=4096. My PChas IP-number 192.168.1.1, and there is only the PC and the PLC on that network.

Are there more settings that I need to alter to be able to connect with a telnet clent?

Here is my code:

[code]
DATA_BLOCK vars FBTest
BEGIN
END_DATA_BLOCK

FUNCTION_BLOCK FBTest
VAR
test_str : STRING[20]; // my test string

net_send : TSEND; // instansiate network TCP/IP send function
net_rcv : TRCV; // instansiate network TCP/IP receive function
net_con : TCON; // instansiate network TCP/IP connect function
net_discon : TCON; // instansiate network TCP/IP disconnect function

net_settings : UDT65;
net_connected : BOOL := FALSE;
net_conn_req : BOOL := TRUE;
net_send_req : BOOL := FALSE;
END_VAR

VAR_TEMP
pStr : ANY;
net_len : INT;
END_VAR

BEGIN
IF NOT net_connected THEN // If not connected, try to connect
net_settings.local_device_id := B#16#03; // use internal ethernet interface
net_settings.local_tsap_id[1] := B#16#00; // port 4096 LSB
net_settings.local_tsap_id[2] := B#16#10; //port 4096 MSB
net_con(REQ := net_conn_req, // try to connect
CONNECT := net_settings, // using default struct with changes from above
ID := 1); // connection ID?
IF net_conn_req THEN
net_conn_req := FALSE; // set back to zero to create positive edge later
END_IF;
IF net_con.DONE OR net_con.ERROR THEN // opertion finished, either good or bad
net_connected := net_con.DONE; // update connection state with result of operation
net_conn_req := TRUE; // try again if needed
Q0.7 := net_con.DONE; // indicate connection status on LED
END_IF;

ELSE // if connected send hello world
test_str := 'Hello world'; // create 'Hello World' string
pStr := test_str; // Point DB pointer at string var
net_len := LEN(s:= test_str); // Calculate length of string
net_send(REQ := net_send_req, // try to send hello world string
ID := 1, // connection ID?
DATA := pStr + 2, // point at beginning of strng data
LEN := net_len); // use length of string
IF net_send_req THEN
net_send_req := FALSE; // set back to zero to create positive edge later
END_IF;
IF net_send.DONE OR net_send.ERROR THEN // opertion finished, either good or bad
net_send_req := TRUE; // try to send string again
END_IF;
END_IF;
END_FUNCTION_BLOCK


ORGANIZATION_BLOCK Cycle

VAR_TEMP
info: ARRAY[0..19] OF BYTE; // prevent strange error while downloading
END_VAR

BEGIN
FBTest.vars(); // call net test function
END_ORGANIZATION_BLOCK

[/code]

The error code returned in STATUS is 80B8, but that is not much help to me as I can't find the list of error codes returned by TCON, does anyone know where to find it?

first of all I would like to ask you a little question. Did you keep the default Subnetmask STEP7 provides for the 192.168.2.2 Address you use? If so you use a Class C network with a Subnetmask of 255.255.255.0, isn't it?
If so you will never connect with an IP 192.168.1.1 (PC Address)to this PLC due to the wrong network address.

If you insist on your 192.168.1.1 on PC side, why don't you use a 192.168.1.2 on the PLC? Secondly have you ever tried to monitor the traffic you create between the PC and the PLC by tools like Wireshark? This way you may notice what happens at the beginning... while the 3-way-handshake happens.

One more thing, why dont you use the Open Communication Wizard to get a reference for the right UDT or DB??

Best regards

New question published by machine00 is split to a separate thread with the subject need STATUS code list for function FB65 TCON.

Best regards
CS Moderator