VTI Instruments EX1629 User Manual page 89

Host Computer
The following sample code segment illustrates a very basic use of the streaming data interface.
The callback function, stream_callback, just prints the timestamps and data values to a FILE
handle. The FILE handle, as well as a sample count total variable, are stored in a user-defined data
structure. A pointer to this structure is passed to the vtex1629_enable_streaming_data function,
along with a function pointer to the streaming callback function. Later, when streaming data pages
(scans) are received, a pointer to the acquisition data, along with the pointer to the user-defined
data structure, are passed to the callback function. The user-defined data structure pointer is passed
as a void* and should be cast to the appropriate type within the callback function.
#define INSTR_LANGUAGE_SPECIFIC
#include<vtex1629.h>
typedef struct {
FILE
ViInt32
} user_struct;
user_struct my_struct = {0};
ViInt32 stream_callback( void *priv, EX1629_rpc_datapage *data )
{
user_struct
ViInt32
ViInt32
priv_struct = (user_struct *)priv;
/* Loop through all of the datasets in the datapage. */
for( ds_idx = 0; ds_idx < data->dataset.dataset_len && ds_idx <
EX1629 Programming
`
User callback
User callback
User callback
User callback
User callback
time
F 6-3: S
IGURE TREAMING
*fout;
sample_count;
*priv_struct; // pointer to user structure
ds_idx;
smp_idx;
MAX_NUM_DATASETS; ds_idx++ ) {
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SHUNT
CAL
RES
PWR
HD
LAN
0 2 4 6 8 10 12
time
D W U C
ATA ITH SER ALLBACK
// dataset index
// sample index
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15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45
SHUNT SHUNT
CAL CAL
RES RES
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
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