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i DATA SERVER FUNCTIONS IV. OPERATION B-63644EN/02
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6.1.8.1 How to use the buffer mode
The buffer mode is designed to handle an NC program larger than the
capacity of the Fast data server built-in ATA card. This mode can be
used with DNC operations (Section 6.6) including a DNC operation by
a subprogram call (M198) (Section 6.7).
In the buffer mode, the Oxxxx file called during a DNC operation or by
subprogram calling is a file list, which is a list of file names arranged in
the sequence in which they are to be called. In this mode, the Fast data
server calls the files specified according to this file list sequentially and
supplies data from them to the NC. (See the following figure.)
As seen from the above figure, the contents of the files (file1 to file5)
specified in the file list in the host computer are fetched into the Fast
data server built-in ATA card, using the FTP, then the data is supplied
to the CNC. In the buffer mode, after the CNC requests the data server
to read the NC program, the specified file list is read from the host
computer, and the contents of the first file in the file list are read, then
the data is supplied to the CNC. Note, therefore, that a time lag occurs
between the read request and the data supply sequence. In addition,
while data is being supplied from one of the areas to the CNC, data is
fetched into the other area, using the FTP. Therefore, the original data
must be divided to such a size that the resulting two consecutive files
can fit on the Fast data server built-in ATA card.
When a data transfer from one of the areas to the CNC is completed, if
the FTP communication with the other area has not ended, another data
supply sequence cannot be performed, and therefore, the program call
ends in an error. This error can be suppressed, using a parameter,
however. See Section 4.3, "Parameters," of Part III, "Setting," for
details. For a DNC operation by a subprogram call (M198), the name of
the file list must be Oxxxx (where xxxx represents a four-digit number).
For other DNC operations, however, the name of the file list is arbitrary.
The name of each file specified in the file list can be any name
permitted in the host computer, provided that it does no exceed 255
alphanumeric characters. In the file list, each file name must be
followed by at least one LF (0A in hexadecimal) or CR (0D in
hexadecimal).
Contents
of Oxxxx
file1
file2
file3
file4
file5
Hard disk
get (FTP)
Program
calling
Oxxxx
Oxxxx
file1
file2
file3
file4
file5
file1
file2
file3
file4
file5
Hard disk
rea
rea B
CNC
Data server Host com
uter