Programming READ_VAR Function to Read Modbus TCP Device Data | Schneider Electric Support

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  • Опубликовано: 10 дек 2024

Комментарии • 5

  • @rajk5326
    @rajk5326 4 года назад +2

    I believe the value 10 in the GEST array is timeout in 100ms time base, not the exchange length. 100 is the exchange length.

    • @baconology3065
      @baconology3065 4 года назад

      Yes, thank you, came here to say that upon checking READ_VAR documentation, specifically the RANK 3 WORD. Video could do a better job at explaining the management table.
      GEST ARRAY [0..3] OF INT
      Exchange management table consisting of the following words:
      Rank 1 word: a word managed by the system and consisting of two bytes:
      Most significant byte: exchange number
      Least significant byte: activity bit (rank 0) and cancel bit (rank 1)
      NOTE: The cancel bit is only available for Modicon M340 and M580 PLCs.
      Rank 2 word: a word managed by the system and consisting of two bytes:
      Most significant byte: operation report
      Least significant byte: communication report
      Rank 3 word: a word managed by the user which defines the maximum response time using a time base of 100 ms (SEE TIMEOUT BELOW).
      Rank 4 word: a word managed by the system which defines the length of the exchange.
      Timeout determines the maximum waiting time for the response. The time base for this parameter is 100 ms (the value 0 corresponds to an infinite waiting value).
      When the timeout elapses, the exchange is ended with an error report. Also, the system does not accept any responses after the end of the timeout.
      Example
      NOTE:
      The timeout is evaluated every second.
      The value of a communication function's timeout must be sufficient to ensure that the response to the question asked is received (use of an external modem on a protocol-based link, for example).
      For Modbus master communication, application timeout set under the communication functions must be greater than the configuration screen timeout multiplied by the number of retries (hardware timeout).
      Communication EFs timeout (as WRITE_VAR or READ_VAR) must be greater than communication master equipment timeout (answer delay).
      See the help file "Structure of the Management Parameters"

  • @jeremyg4249
    @jeremyg4249 5 лет назад +1

    Does the "Directly represented array variables" Section affect the function of the READ_VAR as well? Only the "Allow dynamic array" selection was called out as a must have selected but you selected the aforementioned first.

  • @ANKITKUMAR-og1dm
    @ANKITKUMAR-og1dm 6 лет назад

    Hello sir
    plz give me a example of ATV DRIVE RUN WITH M340 ON MODBUS
    IN FBD FORMET