USER’S MANUAL__________________________________________________________________
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3.3.4 Socket Interface
The RVP902 is configured to listen on a network port. It is ready to
interface to a host computer through the network using a program called
DspExport. When IRIS/Radar is installed onto the same RVP902
computer, it is already configured to communicate with RVP902 processes
through the native interface, bypassing the socket interface. The RVP902
also comes with some built-in utilities such as setup, dspx, and ascope.
These utilities are described in the IRIS Utilities Manual. Because the
RVP902 can only have one program controlling it at a time, use of a local
program like dspx blocks network access, and vice versa.
3.3.4.1 How DspExport Works
DspExport is a daemon program, which is normally configured to run all
the time. When it receives a socket connection request, it establishes a
connection to the RVP902. At this point, multiple connections are allowed.
It only handles the "INFO", "SETU" and "OPEN" commands. Once the
"OPEN" command is sent, an exclusive connection for I/O to the RVP902
is established. If a second OPEN request comes in while the first is still
active, it fails, and returns the message "Device allocated to another user".
To see if it is running on your RVP902, type:
$ ps –aef | grep DspExport
During development, it can always be started up manually by typing
"DspExport" at a shell prompt. It can be started with the "–v" option for
more detailed logging. It defaults to using port 30740. If you wish to use
another port, start it with an option such as "–port:12345". The command
line option "–help" lists these options.
3.3.4.2 Source Examples
The source code for DspExport, and for the dsp library, is supplied on the
RVP902 release cdrom. This is always installed as part of the install
procedure, discussed in IRIS Software Installation Manual. DspExport is
in ${IRIS_ROOT}/src/rda/dsp, and the dsp library is in
${IRIS_ROOT}/base/dsp_lib. In the library, example code is provided,
which talks to DspExport in file OpenSocket.c, dsp_read.c, and
dsp_write.c. Search for the string "SOCKET", and you can see how the
code differs between SCSI interface and socket interface.
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