L.S.,

I'm new to create TCP-communication and so I'm asking for all help I could get.

The job were I'm busy:
- ET200sp (6ES7-510-1DJ01-0AB0).
- ProfiNet network with machine hardware for the process.
- Request for communication over TCP/IP to a WarehouseManagementSystem (WMS).

There will be approx. 12 points of communication for product-info and approx 5 points of communication for general status of the equipment.

I have read a lot of entries in the forum, but because I'm a beginner with S7-1500 and TCP/IP I'm confused how to begin and how to create all parts of the program.
I've found the information about 'TSEND_C' and 'TRCV_C' and they look likes I can use them.

I have read the document in this entry:
- entry: <https://support.industry.siemens.com/cs/document/67196808/how-do-you-program-the-tsend_c-and-trcv_c-instructions-for-open-user-communication-over-the-integrated-profinet-interface-of-the-s7-1200-cpu?dti=0&dl=en&lc=de-DE>
- document: <https://support.industry.siemens.com/cs/attachments/67196808/NET_S7-1200_ISOonTCP_en.pdf>

I guess I can use this also for TCP/IP communication as well, can't I?

I prefer to have 1 DB (with structs of arrays) for the status and 1 DB for the Data to be transmit and received. But I found that the 'Connect' is not accepting this idea.

• Should there be a set of 'TSEND_C' and 'TRCV_C' for every connection?
• Or can/must it be organised by the 'REQ' and 'EN_R' in the program and have only 1 set of 'TSEND_C' and 'TRCV_C'?
  So should the 'REQ' and 'EN_R' be controlled in all the communication-channels?
  And at the same time prepare the correct data for the concerned communication-point?

I have prepared my first trial. And made some screenshots for explaining the problems and what I want to do.  I can't upload all info for this small project.... it is bigger then the allowed attachment of 3072... Instead I have uploaded the screenshots.

How can I upload the project, it is only 3.123kB???

All kind of help is welcome 

Hello,

I can give my opinions for your situation, hope some guys gives also their opinions.

1. yes you can create more connections on same port, they can differ with ID, look to your CPU spec. for how max. connections you can create.

2. I think setting up connections inside T instructions are enough, never used other system. Simply think that this is user communication, other type of connections (DP, Profinet f.ex.) you'll prepare in Network view.

3. T blocks are ok for your project.

4. I think TCP type connection can be used in case of probably PC partner type device.

5. In my opinion never use same DB for connection and I/O buffer. Leave that connections DBs with their life and create your I/O buffers as another defined DBs. I think better use everytime, my experience.

6. In case of multiple connections, use different T blocks with their own DB blocks, you can probably better view on code what are that instructions for. You can use one T block with parametrized other connections, but I think no good idea, maybe chaos and also not good debug possibility.

Hope give you some useful infos for start.

Hi Duris_I,

Do you have a project were you have implemented the communication with TSEND_C and TRCV_C in a working network? I prefer ET200sp, but every S7-1500 will do 
As written before, I have found an example (S7-1200) at Siemens, but that is showing only the Blocks. I do have an idea to solve it, but it would be a good idea to have a reference project.

In my project I have to communicate from several positions in the equipment. When the product is arriving Tx-sent a message with acknowledge, followed by Rx-waiting for an order for that product with ack. Also when there is a fault in the system coming and going a message should be Tx-sent with ack.

What I would also like to know is how the program should react on errors while communicating and how to solve it. e.g. connection lost or reaction for ack is very slow. Is it a good idea to continue sent the message again and again when the ack is not coming? And when is a buffer necessary for store new message when there is a problem with the communication?

Regards,
Willie

Hi Willie,

very sry about sharing some my projects, you know we have own agreements on job, very sry. But first idea what going through my head, what type of communication frames you'll have with WMS system? Why that my idea, simply your thoughts are right, also to that error handling. Sry if I don't understand your situation, simply WMS system is Server or your HW? Do you programm other stations as own living systems but connected to this same net but different with IP? I can imagine message system with strictly defined requests and answers to them (WMS-PLC). Also for correct message integrity I expect some CRC mechanism, ask WMS boys for that possibility. I see this area as important (till this time I don't know exactly about this), you probably know. Also I don't know about that WMS system nothing, can you post some infos? Probably if we will have infos, we can discuss next. Sry Willie, but if you agree, only some hints, some ideas, direction can give you. Also hope that other guys will give their opinions, recommendations.

Hi Duris_I,

Thanks (again) for your reply.

The document, from the friends of WMS, for data-exchange is not as complete as I would like. We have to discuss this next week.
What is clear at the moment is that I need to transfer a block of 52 bytes/26 words of payload to WMS and receive the same amount of data in reply. Both for sending with ack or receiving with ack. The ack is called an echo in the document, sending the same header, but the payload is reset to empty data. A counter value in the header should be the identification of the original sendet message. All message from 1 PLC will be sent to the WMS, and the other PLC is doing the same. Both PLC's do have their own IP-address, the WMS will have have only 1 IP-address (of course).
In the document is written that in case WMS is the sender, then WMS is client and PLC is server (PLC with port 2036). And when the PLC is the sender, the PLC is client (PLC with port 2035) and WMS is server. I've no idea if this is possible with one set of TSEND_C/TRCV_C.
Also in the document they write that in case the ack is not arrived in time, the message should be sent again. Ans as I've understand, this should be repeated till the ack (with the same counter value for indication who the sender was) is received.

What do you mean with the CRC mechanism? Should this be done in the data to be transferred between PLC<>WMS? Or can be relied that the hardware is taking care of it?

Regards,
Willie

Hi Willie,

by my quick look it can be solved without problems. Simply you'll need create 2 connections with different IDs, one as Client, second as Server, all will differ by Port number. You'll use same FB T blocks but each of SEND+RECV will need their own instance block, simply you must differ statuses and also I/O buffers. I think that CRC should be implemented, also on WMS and your side, discuss with WMS boys what CRC type can be best for your communication, simply you must both implement it  

Update: CRC (due type) can be counted with your I/O buffer programatically, then inserted on defined place in buffer and transfered to Server, also you'll receive frame with CRC, need back count for right integrity and only after that use received data, simply this mechanism must be implemented on your and WMS side for right data transfer without error. Discuss this with WMS, I recommend it.

Thnx Kaulquappe for entering this discussion. I think that all what Willie explained I fully understand. Simply his situation is like my, for all my long years previous job, design/creating user defined frames for Exchange needed data between automation and partner, for my situation for most user defined applications on PC and also with external devices. I understand system of frames with ack system, some of this system I had with TCP cammera in automotive areas or PC applications, TCP RFID systems. Also CRC mechanism was implemented on many 'my' devices, like that RFID servers. Therefore I gave recommendation to Willie for discussion with WMS team, they must say if CRC is needed or not. I feel that design of frames will Willie discuss with WMS next time, simply in case of user defined frames. Other case can be Modbus TCP protocol in this case, therefore I ask also about this, but as I looking to our posts, probably not in this case. Hope fruitful discussion here

Update: but Kaulquappe posted one good idea about mixing devices role. Question can be also how this is expected, if you Willie will have permanent connections on both ports with 2 independed connections (and drive your Send/Recv with some logic) or change your one connection with 2 different ports with also connect/disconnect to/from that both ports (for send/Recv). This point to question which side will definitelly initiate first connection  After that probably all traffic will begin...

I was able to communicate, when I made 2 projects with each a PLC.
Communication setup with:
- TSEND_C and TRCV_C in 1 FB in PLC_1
- TRCV_C and TSEND_C in 1 FB in PLC_2
It worked, even with reading back what has been sent, all in PLC_1

And now I'm trying to copy the settings to my original project for PLC_1.
But now the connection is not working....

In the TSEND_C I get Error-bit high (shortly) with the Status 16#80C5.
In the help (F1) this code can't be found.
Somewhere "TURCV: Receive data via Ethernet (UDP)" I found "80C5 - The remote partner has terminated the connection." But I'm not sure if this is adaptable to TSEND_C as well.

Does someone have the complete list of STATUS for TSEND_C and TRCV_C?

And maybe someone knows what to do to solve this problem.

Regards
Willie

Hello Willie,

what WMS server does, it can accept 2 independed IP different connections? Can you post this info? I'll try simulate Server disconnection today evening if I'll got time to catch that Status for sure.