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ComSiemens library

Alberto Vietri PxC ItalyAlberto Vietri PxC Italy
edited May 2020 in PLCnext Engineer

Hi,

I have a questions about ComSiemens library:

1) How many bytes is possibile to exchange between an AXC F 2152 and a S7-1500?

2) Is possibile to exchange LREAL data types?

3) How many S7-1500 could be read with one AXC F 2152?

 

My customer needs to read 200 LREAL from one or (if possible) more S7-1500 and needs to log this data every 5 s. I think is too fast, what dou you think?

 

Thanks in advance.

Comments

  • Martin PLCnext TeamMartin PLCnext Team

    HI Alberto,

    Here are the answers from the developer of that FB library:

    ========================================================

    1. The length of Bytes which can be transmitted in one telegram is communicated between S7-CPU and PxC-CPU. And the maximum length is shown at the Output "iMaxDataCount" at the Functionblock CoSi_ETH_S7_Link.

    Reading all LREALS together is not possible 200 LREAL = 1600 BYTE --> Minimum 4 Read Jobs neccessary.

    In my tests the length between 2152 and S7-1511 CPU is 452 BYTE.

     

    2. Yes it is possible with the S7-12xx AND 15xx CPU. But there is no Functionblock available.
    The customer can program an own functionblock.

    The customer should use the CoSi_JobInterface for one LREAL Read process.

    • iJobNo ---> free number
    • xStartJob --> Trigger all 5s and reset after Done or Error
    • iDataType --> Refer to "CoSi_ETH_S7_Link.iDB_Numer" description. I think "5 (DB)" in your case.
    • iDB_Number --> Number of the DB in the S7 Project
    • iOffset --> Offset where the first LREAL starts in the S7 DB.
      Offset, from which to be read/written from the Siemens PLC. The
      counter/timer number is to be specified in the case of the counter/timer
      data type, from which is to be read/written. In the case of all other data
      types, the specification is in bytes.
    • iDataCount --> Length in Byte which are read out from the S7-D
    • xReadRequest --> Constant TRUE because this job does READ Processes
    • xWriteRequest --> Constant FALSE because this job does NO Write processes

    With rising edge of xDone the read Data must copied out of the "CoSi_ETH_S7_Link.arrDataBuffer".
    If you want to get seperate LREAL as output use BUF_TO_LREAL with connected arrDataBuffer and following parameters: REQ = Trigger from JobInterface.xDone;  BUF_FORMAT = TRUE;  BUF_OFFS = 0 for the first LREAL; BUF_CNT = 8 BYTE

    The next LREAL starts at arrDataBuffer[8] ... and so on.

     

    3. The count of Connections is limited to the maximum number of open Sockets of the PLCnext Engineer CPU.
    I could not find any information about the exact count in the datasheets. But i heared about hundreds of possible Sockets.

     

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