FB_CMA_ReadCsvFile

Reading of a CSV file and sequential output of the data into a PLC buffer (array).

Data can be recorded, displayed and saved with the TwinCAT 3 Scope. One possible storage format is CSV. Thus, signal data can be stored in a CSV file and read in again later with the FB_CMA_ReadCsvFile. The signal data read in can be transferred as an alternative source of input data to an instance of FB_CMA_Source and thus to the Condition Monitoring analysis chain.

Inputs and outputs

Input parameters

VAR_INPUT
    bExecute        : BOOL := TRUE;       // starts execution (on rising edge)
    bAbort          : BOOL;               // aborts execution (after finishing current ADS communication) 
    sNetId          : T_AmsNetId := '';   // TwinCAT system network address (could be kept empty for local host)
    tAdsTimeout     : TIME := T#1S;       // ADS timeout (only 1 second as condition for a fast data transmission)
    sFileName       : T_MaxString := '';  // CSV source file path and name (located on the system with the specified Net Id)
    sSeparator      : STRING(2) := '$T';  // CSV field separator [e.g. tab '$T' or comma ',' or semicolon ';' or colon ':' or blank ' ']
    nHeaderLines    : UDINT := 0;         // Number of lines in the CSV file which belongs to the header. Data start after header lines.
    bColumn         : BOOL := TRUE;       // select whether the data is placed as column (e.g. TcScope CSV file) or as line
END_VAR
VAR_IN_OUT
    aBuffer         : ARRAY[*] OF LREAL;  // buffer with individual length (do not switch the buffer during one execution)
END_VAR

• bExecute: The function block is called by a positive edge on the input bExecute, if the function block is not already active.
• bAbort: The execution is aborted if this input is set. The function block must still be called until the output bBusy=FALSE, so that an ADS communication that has already started internally can be terminated.
• sNetId: No specification of these input variables is required in order to perform the operation on the local device. Alternatively, an empty string can be specified. To direct the query to another computer, its AMS Net Id (of type T_AmsNetId) can be specified here.
• tAdsTimeout: Specifies a maximum time to execute the internal ADS communication.
• sFileName: Specifies the file path of the CSV file to be read.
• sSeparator: Specifies the CSV field separator used in the CSV file. Individual values are hereby separated from each other.
• nHeaderLines: Specifies the number of rows in which there is only header information. These are skipped when reading out. A CSV file saved with the TwinCAT 3 Scope View can contain different amounts of header information.
• bColumn: Indicates whether the data are located in a row one after the other (bColumn=FALSE) or underneath one another as a column in the CSV (bColumn=TRUE). The latter is the case with CSV files that have been saved with the TwinCAT 3 Scope View.
• aBuffer: Specifies the output data buffer into which the read values are written. This must be a PLC array of the type LREAL of any length. If the FB_CMA_ReadCsvFile is used as an alternative to the hardware sensor signal, the length typically corresponds to the oversampling factor. The specified buffer must be maintained over the duration of the operation. During the operation, the buffer aBuffer is filled several times with new data sets and this is signaled via the output variable bBufferFull.

Output parameters

VAR_OUTPUT
    bBufferFull     : BOOL;     // signals that aBuffer is fully filled
    nReadRecords    : UDINT;    // shows the number of records saved to aBuffer
    bBusy           : BOOL;     // TRUE if execution is active
    bError          : BOOL;     // TRUE if an error occurred
    hrErrorCode     : HRESULT;  // '< 0' = error; '> 0' = info; '0' = no error/info
    ipErrorMessage  : I_TcMessage := fbErrorMessage;    // shows detailed information about occurred errors,warnings and more
END_VAR

• bBufferFull: The output is TRUE if the buffer aBuffer has been completely filled. This will often be the case over the duration of the operation until the CSV file has been read out completely. If a new data set is present in the buffer aBuffer, it should be processed immediately before the function block is called again. Typically, after each call to the function block, new data is available in the buffer. Nevertheless, the output bBufferFull should be checked to ensure a correct data stream.
• nReadRecords: The output indicates how many values the entire read data set contained.
• bBusy: The output is TRUE as long as the function block is active. The output becomes FALSE if the CSV file has been read in full or an error occurred.
• bError: The output is TRUE if an error occurs.
• hrErrorCode: If an error occurs, a corresponding error code of the type HRESULT is output. Possible values are described in the List of error codes.
• ipErrorMessage: Contains more detailed information on the current return value. Refer here to the section Error description and information. This special interface pointer is internally secured so that it is always valid/assigned.