DAZZLER
TM
system manual Part I : installation & operation 6.3
LabView execution model is to follow all the signal paths until held up by not yet evaluated
data. A node present in a block diagram will execute only when data is present at all of its
inputs. After the execution of a node the output data of the node is transmitted to the next
node of the dataflow path. The execution order of the VIs and function on the block diagram
is determined by the movement of data through the nodes. Typically, chaining of the error
signal (error in, error out) defines the order of execution. For signals equivalent in terms of
evaluation, the actual order of evaluation is left to the compiler.
This example demonstrates the compatibility layer with the legacy “text file” remote protocol
described in section 6.2. It basically implements the steps described above : init, call remote
function, close. In addition, timing of the complete transaction is conducted: note the use
of the ”flat sequence” to enforce execution order. The timer readings are done in ”separate
frames”.
The requestor program opens the communication with the Dazzler
TM
by calling the open.Vi
INIT
open.vi
.
The arguments are the host IP address
10
, the port number is defined in the Dazzler INI file, in
the same way as the ’default directory’ (see subsection 5.3.1). The connection is kept open
by the library until the call of close.vi (see below).
The input parameter ”VIs to initialize” is supposed to provide the list of the remote functions
that will be called by the remote program. This is mainly for performance purposes. If not
connected, the library will prepare itself for the execution of every remote function provided in
the toolkit, which takes a lot of time
11
.
The example program next shows the use of the remote funtion which emulates the text file
mode. It does the same things as with files, without actually writing any file to pass information,
which makes it a lot faster.
REQU
dorequest.vi
This VI sends the ”Request Contents” string, without any checking, to the Dazzler program.
The syntax is the same as that of a request.txt file as described in section 6.2. To be totally
freed of the use of files, it is recommended to use the #wave keyword in this request to directly
include the content of the wave parameters, as described in subsection 6.2.6.
The constant ”Timeout(ms)” is the time allowed to wait for an acknowledgment from the
Dazzler program. Its default value of 5 seconds is adequate for most cases.
10
for local traffic on the same computer is standardised to localhost, with IP address 127.0.0.1 while on
the network the machine has a proper IP address
11
Measured improvement: from 260ms ”unwired” down to 35ms ”wired” references.
V3.00 - 8
th
April 2019 (ContentsTable) (FiguresTable) 68/94
To Next Page
Loading...
Need help?
General