Hello.

I am currently doing a project where I need to send and receive data from a linux pc to PLC via TCP/IP using TCON, TRCV and TSEND blocks.

I left the project on a stand-by for now because of my problem with the TSEND block.

It sends the data i've configured it to send, a simple string, but it only sends it when im monitoring the program with TIA portal. I am monitoring the data stream with Wireshark. When I start the CPU I can see that the PLC is establishing the connection. I have a 2Hz clock to send the string, but it wont send anything unless I go online and monitor the OB.

Any idea how to fix this or whats causing this? I am a ***ie when it comes to professionally doing this stuff and I don't have any prior experience dealing with PC - PLC communication.

I am using Siemens Simatic s7-1200 CPU 1214C DC/DC/DC.

Programming software TIA Portal V13 sp1.

With regards,

Ari

EDIT: The testing was done on windows platform.

Hello,

without looking to your project, probably impossible. If you can, share project.

Hi

Test project in attachment. Haven't tried to make it work on my actual project yet, since I cant even make it work on this one. Contains TCON, TSEND and TRCV blocks in OB1 and the configurations for them.

-Ari

Hello,

I was test your project and working for me without problems, also without online monitoring. My Server application receive String from PLC but also some other chars before that string. Your project missing some checking of statuses which can show you success/problems of send/receive data. Look to your instructions help in TIA and implement some checks. Also problem is set on DB that REQ bits, you can set that bits for TCON and next instructions via some memory bits, then you can set/reset that bits in watch table and test all. Also interesting question about LEN=16 and Time of Send, because it runs about 2s interval not 0.5 Hz. Pls make many corrections in your code, also check correct send buffer.

Update: I was change your Send buffer to Array [0..100] of Bytes instead of String, inserted some values to array (you have LEN=16 so I've inserted 16 different values) and now my server receives correct frame as I defined.

Hi, thanks for replying.

I set up some checks for my TCON block. The Busy output stays at state 1 (Status 16#7002) when initializing the block. If im understanding this correctly, the TCON block doesn't make the connection to the PC.

This brought me to another conclusion (maybe). The PLC creates a communication connection with the PC when put into online monitoring mode. The TSEND blocks info says "Send data via communication connection". Does the TSEND use this monitoring connection to send the data?

Could the problem with TCON not making the connection be on my computer itself? Firewall or something of sorts? I did try turning of my firewall for that matter though. Or could the ports im using for TCON be closed/already in use so it wont let me make the connection?

With regards,

Ari

Hello,

ok make simple test with your PLC and your PC/notebook. On PC run Hyperterminal but connection set to TCP/IP also with defined IP - 192...241 and Port 9000, these settings you have on connection. Then PLC will send cyclically to your hyperterminal frame. Give info about functionality.

Update: yes if you have some Antivirus (filter incomming/outgoing data on ports), disable it.

Hi again.

Tested the program with hyperterminal. Didnt work at first, disabled all protection software from PC and it started working. With small adjustments I even got this semi-working on the linux PC. Still need to tweak the connection program but this did help me get started and now I can focus on other things.

Thanks for your help!

With regards,

Ari