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LoadFromFile - method of object PmBuffer

Description:
Reading values from binary file into the data block.
Syntax:
Long LoadFromFile(Long nOffset, String sFile, [Long nFileOffset], [Long nLength])
Calling:
Value = PmBuffer.LoadFromFile(nOffset, sFile, nFileOffset, nLength)
Parameters:
nOffset(Long) Defines the position of written value in the data block.

The whole written item muyst be inside the data block, or the whole item is added to the end of the data block. The item is written either whole or not read at all.

>= 0 - Index (in bytes, zero-based index) in data block.
-2 - The whole item is added to the end of the data block. The size of the data bloc is then increased by the written item.
-4 - The internal automatic position is used (see AutoOffset). It points behind the last read or written value and increases continually.

If the items are read/written one by one then it is not necessary to define the position, but it is better to use this automated positioning.

sFile(String) The file name with the path. If a full path is not entered, then it is completed relative to the application file folder.

It is recommended to use the PROMOTIC path syntax - see PROMOTIC path to files and folders.

nFileOffset[optional] (Long) Defines the position of read value in the binary file in bytes. The value 0 (default) means reading from the beginning of the file.
nLength[optional] (Long) Defines the number of read bytes. The value -1 (default) means reading from the start of the file.
Return Values:
Returns the number of really read bytes
Note:
This method is not functional for Web panels.
See also:
Reading from file:
For inverse example see Writing into file.
JavaScriptVBScriptSelect and copy to clipboard

var oBuf = Pm.CreatePmBuffer();
oBuf.SetSize(3);
oBuf.LoadFromFile(-4, "#data:Test.bin", 0, 1);
oBuf.AutoOffset = 0;
Pm.Debug("GetInt16 = " + oBuf.GetInt16(-4));
Pm.Debug("GetInt8 = " + oBuf.GetInt8(-4));
Pm.Debug("Hex = " + oBuf.GetHexaString(0));

History:
Pm9.00.05: Created
PROMOTIC 9.0.6 SCADA system documentation - MICROSYS, spol. s r.o.

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